Vaccine Considerations for New and Expectant Moms

New and expectant moms often have questions related to vaccines as this period of life often involves conversations and decisions related to vaccines. Expectant moms, their babies, and even those who will be around their babies, may need vaccines.

In some cases, vaccines protect pregnant women as the changes related to pregnancy make them more susceptible to infections, but in other cases, the vaccines are meant to protect the baby. Questions sometimes relate to special circumstances, such as premature birth or breastfeeding, or to other children in the home of the pregnant woman or new baby.

The information below addresses each of these issues. If you can’t find the answer to your question, please email your question to vacinfo@email.chop.edu, so we can help you.

Pregnant women

When a woman is pregnant, two changes related to her immune system can make her more susceptible to certain infections:

  • Suppressed immune system function — Because the growing fetus is not identical to his mom genetically, the female body has to undergo changes so that it does not “reject” or “attack” the fetus as a foreign entity.
  • Physical changes — As the pregnancy progresses, increased fluid volume adds stress to the heart and lungs making women more susceptible to infections, such as influenza, compared to non-pregnant women of the same age.

Read more about pregnant women and immunity in this Q&A.

Important vaccines during pregnancy

  • Influenza. Women who will be pregnant during the influenza season should receive the inactivated flu vaccine (flu shot). Pregnant women are at increased risk for influenza-related complications that require hospitalization.
  • Hepatitis B. Because many people do not know that they are infected with hepatitis B virus, and because an infant can get the disease at birth from an infected mother, your obstetrician will perform a blood test to determine whether you are infected with hepatitis B. If you are, in addition to getting vaccinated shortly after birth, your baby will be given an antibody preparation to prevent him or her from getting the disease.
  • Tdap. During each pregnancy, women should receive a dose of Tdap vaccine between 27 and 36 weeks’ gestation. While anytime during this window is fine, public health officials suggest getting this vaccine earlier rather than later. Women who did not receive the vaccine during pregnancy should get it immediately after giving birth. Dads, grandparents, and other teens and adults who will be around the baby should also get a dose if they have not had the booster.
  • Pneumococcal. If a woman is considered high risk for pneumococcal disease, she should get this vaccine. High-risk conditions include chronic disorders of the pulmonary system (but not asthma), cardiovascular disease, diabetes mellitus, chronic liver diseases, chronic renal failure, asplenia (including sickle cell disease), immunosuppressive conditions (i.e., HIV, leukemia, lymphoma, multiple myeloma, Hodgkin's disease, generalized malignancy, or organ or bone marrow transplantation), treatment with certain medications, or cochlear implants.

Vaccines to avoid during pregnancy

  • MMR. Women who are pregnant should not receive live, weakened viral vaccines, including the ones for measles, mumps and rubella (MMR). A woman should avoid becoming pregnant for four weeks after receipt of the MMR vaccine.
  • Varicella and shingles. As with MMR, these vaccines contain a live, weakened virus and should not be given to pregnant women. Additionally, women should avoid becoming pregnant for at least one month after receipt of either of these vaccines.
  • HPV. Women who have started the series before becoming pregnant should wait until after delivery to get the remaining doses.

If you have inadvertently received any of these vaccines during pregnancy, you should be aware that none has been proven to be harmful to your unborn baby. The recommendation to avoid these vaccines is theoretical. In some cases, databases are maintained by the manufacturers to track these occurrences, so if you receive one of these vaccines, you or your doctor should report it to the manufacturer:

  • Varicella-containing vaccines (varicella, MMRV, or shingles): Call 1-877-888-4231.
  • HPV vaccines: For Gardasil® call 800-986-8999.

Children in the home of someone who is pregnant

Children living in the home of a pregnant woman can receive all recommended vaccines.

Are you on Pinterest?

The VEC curated a Pinterest board specific to the needs of pregnant women. It includes a collection of VEC resources for pregnant women.

Breastfeeding

Baby

Infants who are being breastfed may receive all 14 vaccines routinely recommended for infants. Antibodies in breast milk do not interfere with any of the currently recommended vaccines.

Sometimes parents wonder whether they can forego immunizations for their baby because the baby is being breastfed; however, this is not the best decision since antibodies in human breast milk bathe the intestinal surface, but are not absorbed. Therefore, breast milk antibodies never enter the bloodstream where they would be needed to protect against certain diseases. Examples of these types of diseases include diphtheria, tetanus, pertussis; measles, mumps, rubella; varicella (chickenpox); pneumococcus; Haemophilus influenzae type b; polio; hepatitis A and hepatitis B.

Mom

Women who are breastfeeding can receive any vaccines they need during this time. Although some live viral vaccines may replicate and cause viruses to be excreted in breast milk, the viruses are weakened sufficiently that they will not harm the baby.

In most cases, women are recommended to have received the live viral vaccines (specifically, MMR and chickenpox) prior to becoming pregnant because the diseases they prevent may be harmful to a developing fetus if the woman is infected during pregnancy.

Preterm infants

Any baby born before the 37th week of pregnancy is considered to be preterm. About 12 percent of births in the United States are preterm.

Maternal antibodies

Preterm babies acquire lesser quantities of antibodies through the placenta than full-term babies. Since these antibodies are present at lower levels, they do not last as long as those of full-term babies. Because preterm infants rely on their own immune systems for protection sooner than full-term babies, it is important that they receive needed vaccinations so they can protect themselves against disease.

Chronologic age

Vaccines should be given according to a baby's chronologic age — the time since delivery.

Hepatitis B vaccine

Preterm infants of mothers infected with hepatitis B should receive the hepatitis B vaccine at or shortly after birth. If the baby weighs less than 2,000 grams, the dose should not be counted as part of the hepatitis B series, and the baby should start the three-dose series one month after birth.

Preterm infants of mothers who are not infected with hepatitis B should get the vaccine one month after birth.

Preterm babies discharged before 1 month of age may get the vaccine at discharge as long as they are considered medically stable and have been consistently gaining weight.

In both cases, later doses should be given at least four weeks after the dose at 1 month. The third dose should be given at least 16 weeks after the first dose and at least eight weeks after the last dose, but not before 6 months of age.

Vaccines typically administered at 2 months

In addition to hepatitis B, 2-month-old babies require vaccination against diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type b, pneumococcus and rotavirus. Preterm infants should receive these vaccines at the chronologic age of 2 months, even if they are still hospitalized.

These vaccines should continue to be given at the appropriate chronologic ages according to the Centers for Disease Control and Prevention's vaccine schedule until each series is completed.

Other vaccines

Other vaccines should also be given according to the recommended schedule; these include vaccines for measles, mumps, rubella, varicella and hepatitis A.

Influenza vaccine is not recommended until 6 months of age. At 6 months of age, the baby may get the inactivated version of the vaccine. Healthcare workers and family members in contact with a baby less than 6 months old should be immunized to lessen the baby's chance of being infected with influenza.

Vaccines: Birth to 2 years of age

For questions related to the vaccines your baby is recommended to receive in the months after birth, the following resources are available:

Other questions you may have

Can someone who had a live, weakened viral vaccine (e.g., MMR, chickenpox, shingles, nasal influenza, rotavirus, or outside of the U.S., oral polio) be near a new baby or a pregnant woman?

Yes. Although these vaccines contain live, weakened viruses, recently vaccinated people are not likely to spread the virus after vaccination, with a few exceptions:

  • If a person who got the chickenpox vaccine develops a rash, they should take precautions to ensure that the baby, or an unvaccinated pregnant woman, does not come into contact with the sores as they may contain the weakened virus and could, theoretically, spread to the unprotected baby or pregnant woman.
  • Weakened, live polio virus can spread following vaccination; however, the weakened virus is not likely to cause disease. In fact, in the case of polio vaccine virus, when unvaccinated people come into contact with it, they can get infected and gain immunity without experiencing illness or being vaccinated. This is called contact immunity. Because pregnant women typically have immunity, and babies receive polio vaccine in the first few months of life, no special precautions are needed.

What do I need to know about Zika virus and how to avoid it if I am pregnant?

Zika virus is spread through mosquito bites. Most people who are infected do not have any symptoms and a few (about 1 in 5) will have symptoms such as fever, rash, joint pain or pink eye. The most concerning aspects of Zika virus infection are for pregnant women because of the adverse effects on the developing fetus.

Read the Zika Virus: What you Should Know Q&A sheet for more information.

Should medicine be given before a child gets vaccinated to prevent or control fever?

Fevers are actually a sign that the immune system is responding to a challenge. If children are given fever-reducing medications before vaccinations, they may not develop a fever, but their immune response to the vaccines may also be lower.

Read the Infectious Diseases and Fevers: What You Should Know Q&A sheet for more information about fevers, what they are, and how to treat them.

Additional resources

Materials developed by the Vaccine Education Center at Children’s Hospital of Philadelphia:

  • Infectious Diseases and Pregnancy: What You Should Know — this question-and-answer sheet addresses vaccine and immunity topics relevant to pregnant women.
  • Vaccines and Your Baby — this video and booklet series describes vaccines commonly given in the first few years of life and the diseases they prevent.
  • Vaccines on the Go: What You Should Know — this free mobile app is available for iPhone and Android devices. In addition to easily having vaccine information any place you need it, you can email the VEC with questions and view additional resources including Q&A sheets and videos.
  • Are Maternal Antibodies Considered When the Vaccine Schedule is Made? — in this video, Dr. Offit talks about how the transfer of maternal antibodies impacts the creation of the vaccine schedule.

Immunization for Women is an immunization website offered by the American College of Obstetricians and Gynecologists (ACOG) that includes pregnancy information for expectant women.

The Centers for Disease Control and Prevention (CDC) also offers a variety of materials related to maternal vaccinations.

References

HPV vaccine

Kharbanda EO, Vazquez-Benitez G, Lipkind HS, Sheth SS, Zhu J, et al. Risk of spontaneous abortion after inadvertent human papillomavirus vaccination in pregnancy. Obstet Gynecol 2018;132(1):35-44.
The authors evaluated the risk of spontaneous abortion following quadrivalent HPV vaccination given before and during pregnancy during a 7-year period. No differences in the risk of spontaneous abortion were identified when comparing those who had received vaccine 16 to 22 weeks before their last menstrual period versus those vaccinated either within 6 weeks of last menstrual period or during the first 19 weeks of pregnancy. The authors concluded that HPV vaccine did not increase the risk of spontaneous abortion in the 6 weeks preceding pregnancy or during pregnancy. 

Lipkind HS, Vazquez-Benitez G, Nordin JD, Romitti PA, Naleway AL, et al. Maternal and infant outcomes after human papillomavirus vaccination in the periconceptional period or during pregnancy. Obstet Gynecol 2017;130(3):599-608.
The authors evaluated whether quadrivalent HPV vaccine administered during the periconceptional period or during pregnancy was associated with increased risks for adverse outcomes. The authors compared outcomes between those women vaccinated two weeks before or two weeks after their last menstrual period with women who were vaccinated four to 18 months before their last menstrual period. Administration of quadrivalent HPV vaccine in the periconceptional period or during pregnancy was not associated with an increased risk of preterm delivery, small for gestational age, chorioamnionitis, hypertensive disorders of pregnancy and gestational diabetes, or more than 50 selected major structural birth defects.

Scheller NM, Pasternak B, Molgaard-Nielsen D, Svanstrom H, Hviid A. Quadrivalent HPV vaccination and the risk of adverse pregnancy outcomes. N Engl J Med 2017;376(13):1223-1233.
The authors assessed the risk of adverse pregnancy outcomes after quadrivalent HPV vaccine exposure during pregnancy in Danish women. Exposure to the quadrivalent HPV vaccine was not associated with significantly higher risks for major birth defect, spontaneous abortion, preterm birth, low birth weight, small for gestational age, or still birth.

Moreira ED, Block SL, Ferris D, Giuliano AR, Iversen OE, et al. Safety profile of the 9-valent HPV vaccine: a combined analysis of 7 phase III clinical trials. Pediatrics 2016;138(2):e20154387.
The authors evaluated the safety profile of the 9-valent HPV vaccine in seven phase III studies. Pregnancy outcomes, including those among live births through the first six weeks of life, were analyzed among nearly 3,000 pregnancies that occurred during the study period. The incidence of adverse pregnancy outcomes was compared between quadrivalent HPV and 9-valent HPV vaccines. The authors found no difference in the number of fetal losses (e.g., spontaneous abortion, late fetal death, etc.), or the incidence of congenital anomalies between the groups. Additionally, the proportion of pregnancies with adverse outcome were within ranges reported in the general population. 

Baril L, Rosillon D, Willame C, Angelo MG, Zima J, et al. Risk of spontaneous abortion and other pregnancy outcomes in 15-25 year old women exposed to human papillomavirus-16/18 AS04-adjuvanted vaccine in the United Kingdom. Vaccine 2015;33:6884-6891.
The authors assessed the risk of spontaneous abortion and other adverse pregnancy outcomes after inadvertent exposure to HPV-16/18 vaccine surrounding gestation during a three-year period.  Investigators found no increased risk of spontaneous abortion, still birth, preterm or post-term birth, small or large for gestational age, or infant death before 12 weeks when comparing those women who became pregnant within 30 days before or 45 to 90 days after vaccine receipt versus those who became pregnant 120 days to 18 months after the last HPV vaccine dose. 

Panagiotou OA, Befano BL, Rodriguez AC, Herrero R, Schiller JT, et al. Effect of bivalent human papillomavirus vaccination on pregnancy outcomes: long term observational follow-up in the Costa Rica HPV vaccine trial. BMJ 2015;351:h4358.
The authors examined the effect of the bivalent HPV vaccine on miscarriage by comparing women who received HPV vaccine, hepatitis A vaccine, or no vaccine. The three groups did not differ in their incidence of miscarriage after adjusting for age at vaccination and age at conception.

Wacholder S, Chen BE, Wilcox A, Macones G, Gonzalez P, et al. Risk of miscarriage with bivalent vaccine against human papillomavirus (HPV) types 16 and 18: pooled analysis of two randomized controlled trials. BMJ 2010;340:c712.
The authors evaluated the risk of miscarriage after receipt of AS04-adjuvanted bivalent 16/18 HPV vaccine during pregnancy. More than 3,500 pregnancies occurred in the two multicenter phase III trials where the bivalent vaccine was compared to a control group that received hepatitis A vaccine. No differences in the rate of miscarriage were detected between the two groups.

Garland SM, Ault KA, Gall SA, Paavonen J, Sings HL, et al. Pregnancy and infant outcomes in the clinical trials of a human papillomavirus type 6/11/16/18 vaccine: a combined analysis of five randomized controlled trials. Obstet Gynecol 2009;114(6):1179-1188.
The authors analyzed the outcomes of more than 4,000 pregnancies in women who did or did not receive the quadrivalent HPV vaccine. No significant differences were detected between the two groups regarding the proportion of pregnancies resulting in live birth, fetal loss, spontaneous abortion, and congenital anomalies.

Tetanus, diphtheria, and acellular pertussis vaccines

Tavares F, Nazareth I, Monegal JS, Kolte I, Verstraeten T, et al. Pregnancy and safety outcomes in women vaccinated with an AS03-adjuvanted split virion H1N1 (2009) pandemic influenza vaccine during pregnancy: a prospective cohort study. Vaccine 2011;29:6358-6365.
In this prospective, observational study, the authors found that receipt of the AS03-adjuvanted H1N1 pandemic influenza vaccine administered during pregnancy was not associated with an increased risk of spontaneous abortion, stillbirth, congenital anomalies, preterm delivery, low birth weight, or maternal complications including upper respiratory tract infection, urinary tract infection and preeclampsia/hypertension.

Omon E, Damase-Michel C, Hurault-Delarue C, Lacroix I, Montastruc JL, et al. Non-adjuvanted 2009 influenza A (H1N1)v vaccine in pregnant women: the results of a French prospective descriptive study. Vaccine 2011;29:9649-9654.
In this prospective, observational study, the authors described pregnancy outcomes among more than 500 French women who were vaccinated with non-adjuvanted influenza A/H1N1 vaccines. Compared with the general population, vaccination during pregnancy was not associated with an increased risk of maternal complications (e.g., preterm labor, hypertension, gestational diabetes, premature rupture of membranes, infections), congenital malformations (e.g., orthopaedic, renal, genital, cardiologic, ophthalmologic, otologic, among others) or other neonatal disorders (e.g., quadriplegia, hearing impairment, respiratory infection, infectious diseases, among others).

Pasternak B, Svanstrom H, Molgaard-Nielsen D, Krause TG, Emborg HD, et al. Risk of adverse fetal outcomes following administration of a pandemic influenza A (H1N1) vaccine during pregnancy. JAMA 2012;308(2):165-174.
The authors investigated the incidence of adverse fetal outcomes in 7000 Danish women who did or did not receive an adjuvanted influenza A(H1N1)pdm09 vaccine during pregnancy. Exposure to the vaccine, regardless of trimester, was not associated with a significantly increased risk of major birth defects, preterm birth, or fetal growth restriction.

Oppermann M, Fritzsche J, Weber-Schoendorfer C, Keller-Stanislawski B, Allignol A, et al. A(H1N1)v2009: a controlled observational prospective cohort study on vaccine safety in pregnancy. Vaccine 2012;30:4445-4452.
The authors assessed the safety of influenza A/H1N1 vaccination in pregnancy by prospectively following the pregnancies of German women who were vaccinated during pregnancy or ≤ 4 weeks prior to conception and comparing outcomes to unvaccinated pregnant women. The authors found no differences in the risks for spontaneous abortions, preeclampsia, prematurity, or intrauterine growth restriction, or a difference in the rate of major malformations in women who were vaccinated compared with unvaccinated women.

Launay O, Krivine A, Charlier C, Truster V, Tsatsaris V, et al. Low rate of pandemic A/H1N1 2009 influenza infection and lack of severe complication of vaccination in pregnant women: a prospective cohort study. PLoS ONE 2012;7(12):e52303.
In this prospective cohort study, the authors assessed the consequences of maternal receipt of pandemic A/H1N1 2009 influenza on pregnancy outcomes by comparing vaccinated to unvaccinated women. They found no significant difference in pregnancy outcomes (i.e., onset of labor, mode of delivery, gestational age at delivery) and perinatal outcomes (i.e., birth weight, Apgar score, or requirement for neonatal intensive care) between women who received A/H1N1 2009 influenza vaccine and those who didn’t.

Rubinstein F, Bonotti A, Wainer V, Schwarcz A, Augustovski F, et al. Influenza A/H1N1 MF59-adjuvanted vaccine in pregnant women and adverse perinatal outcomes: multicenter study. BMJ 2013;346:f393.
In this multicenter, prospective study, the authors evaluated the risk of adverse perinatal events after vaccination with an MF59-adjuvanted influenza A/H1N1 vaccine in more than 7200 pregnant women. Vaccinated pregnant women were found to have a lower risk of low birthweight, preterm delivery, or fetal or early neonatal death up to seven days postpartum when compared to unvaccinated pregnant women.

Chavant F, Ingrand I, Jonville-Bera AP, Plazanet C, Gras-Champel V, et al. The PREGVAXGRIP study: a cohort study to assess foetal and neonatal consequences of in utero exposure to vaccination against A(H1N1)v2009 influenza. Drug Saf 2013;36:455-465.
In this prospective study, the authors assessed the outcomes of more than 2400 pregnant French women who received the 2009 influenza A/H1N1 pandemic vaccine.  The rate of congenital malformations, spontaneous abortions, still births, preterm deliveries, or neonatal disorders was not higher than the rate reported in the general population.

Chambers CD, Johnson D, Xu R, Luo Y, Louik C, et al. Risks and safety of pandemic H1N1 influenza vaccine in pregnancy: birth defects, spontaneous abortion, preterm delivery and small for gestational age infants. Vaccine 2013;31:5026-5032.
The authors conducted a prospective safety study of women who did or did not receive a pandemic H1N1 monovalent or trivalent influenza vaccine during pregnancy.  No clinically significant differences in the rate of spontaneous abortion, major birth defects, preterm delivery, or small for gestational age were detected.

Kharbanda EO, Vazquez-Benitez G, Lipkind H, Naleway A, Lee G, et al. Inactivated influenza vaccine during pregnancy and risks for adverse obstetric events. Obstet Gynecol 2013;122(3):659-667.
The authors compared the risks of adverse events during pregnancy in women who did or did not receive a trivalent inactivated influenza vaccine. More than 74,000 pregnant women were vaccinated during the 7-year-study period. Vaccine receipt did not confer an increased risk for adverse maternal outcomes such as hyperemesis, chronic hypertension, gestational hypertension, gestational diabetes, proteinuria, urinary tract infection, puerperal infections, venous complications, pulmonary emboli, peripartum cardiomyopathy, preeclampsia or eclampsia.

Ludvigsson JF, Strom P, Lundholm C, Cnattingius S, Ekbom A, et al. Maternal vaccination against H1N1 influenza and offspring mortality: population based cohort study and sibling design. BMJ 2015;351:h5585.
In this Swedish prospective study, the authors investigated the mortality of more than 41,000 pregnancies in mothers who either did or did not receive the influenza A(H1N1)pdm09 vaccine. Mothers vaccinated during pregnancy were not at increased risk of adverse neonatal outcomes such as stillbirth, early neonatal death (first six days of life) or later death (7 days of life up to 4.6 years of age), regardless of the trimester during which they were vaccinated.

Fabiani M, Bella A, Rota M, Clagnan E, Gallo T, et al. A/H1N1 pandemic influenza vaccination: a retrospective evaluation of adverse maternal, fetal, and neonatal outcomes in a cohort of pregnant women in Italy. Vaccine 2015;33:2240-2247.
The authors evaluated the risk of adverse maternal, fetal, and neonatal outcomes in more than 2000 pregnant women in Italy vaccinated during the second or third trimester with the 2009 MF59-adjuvanted A/H1N1 pandemic influenza vaccine. They found no statistically significant association between vaccine receipt and maternal outcomes (i.e., hospital admissions for influenza, pneumonia, hypertension, eclampsia, diabetes, thyroid disease, and anemia), fetal outcomes (i.e, fetal death after the 22nd gestational week), and neonatal outcomes (i.e., preterm birth, low birth weight, low 5-minute Apgar score, and congenital malformations).

Zerbo O, Modaressi S, Chan B, Goddard K, Lewis N, et al. No association between influenza vaccination during pregnancy and adverse birth outcomes. Vaccine 2017;35:3186-3190.
The authors evaluated the association between maternal influenza vaccination during pregnancy and risk of preterm birth, small or large for gestational age, admission to the neonatal intensive care unit, need for mechanical ventilation, respiratory distress syndrome, low birth weight, and low Apgar scores during a 6-year period in more than 145,000 women among whom 64,000 were vaccinated.  The authors found no association between maternal influenza vaccination during pregnancy and increased risk for adverse outcomes.

Kharbanda EO, Vazquez-Benitez G, Romitti PA, Naleway AL, Cheetham TC, et al. First trimester influenza vaccination and risks of major structural birth defects in offspring.  J Pediatr 2017;187:234-239.
The authors examined the risks for major structural defects in infants following receipt of inactivated influenza vaccine in the first trimester during 10 influenza seasons. More than 50,000 mothers received inactivated influenza vaccine in the first trimester during the study period. The authors found no increased risk for cardiac, orofacial, respiratory, neurologic, ophthalmologic, otologic, gastrointestinal, genitourinary and muscular or limb defects in the offspring of women who were vaccinated during the first trimester.

Hviid A, Svanstrom H, Molgaard-Nielsen D, Lambach P. Association between pandemic influenza A(H1N1) vaccination in pregnancy and early childhood morbidity in offspring. JAMA Pediatr 2017;171(3):239-248.
The authors evaluated whether administration of pandemic influenza A(H1N1) vaccination during pregnancy increased the risk for early childhood morbidity. They found that children whose mothers received influenza vaccine during pregnancy were not more likely to be hospitalized in early childhood than those whose mothers weren’t vaccinated, regardless of trimester exposure.

Pertussis vaccine

Fortner KB, Swamy GK, Broder KR, Jimenez-Truque N, Zhu Y, et al. Reactogenicity and immunogenicity of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap) in pregnant and nonpregnant women. Vaccine 2018;36:6354-6360.
In this prospective, observational, cohort study, the authors investigated the reactogenicity and immunogenicity following Tdap vaccination. Moderate or severe reactions were not significantly higher in pregnant compared with non-pregnant women. 

Sukumaran L, McCarthy NL, Kharbanda EO, Vazquez-Benitez G, Lipkind HS, et al. Infant hospitalizations and mortality after maternal vaccination. Pediatrics 2018;141(3):e20173310.
The authors evaluated whether maternal receipt of influenza and Tdap vaccines increased the risk of infant hospitalization or death in the first six months of life during a 10-year period. They found no association between vaccination and infant all-cause hospitalization, hospitalization from respiratory causes, or mortality.  

DeSilva M, Vazquez-Benitez G, Nordin JD, Lipkind HS, Klein NP, et al. Maternal Tdap vaccination and risk of infant morbidity. Vaccine 2017;35:3655-3660.
A slight increase in the risk of chorioamnionitis in women vaccinated with Tdap during pregnancy was previously detected in two previous Vaccine Safety Datalink (VSD) evaluations. In this study, the authors investigated the clinical significance of these findings by reviewing four years of data from seven VSD sites, including more than 45,000 women vaccinated during pregnancy. An increased risk of chorioamnionitis was observed in women vaccinated during pregnancy compared to those who were not vaccinated. Despite these findings, no increased risk of clinically significant outcomes typically associated with chorioamnionitis was found in infants born to Tdap-vaccinated women, including transient tachypnea of the newborn, neonatal sepsis, neonatal pneumonia, respiratory distress syndrome or newborn convulsions. 

Layton JB, Butler Am, Li D, Boggess KA, Weber DJ, et al. Prenatal Tdap immunization and risk of maternal and newborn adverse events. Vaccine 2017;35:4072-4078.
The authors evaluated the relationship between Tdap vaccination during pregnancy and adverse birth outcomes in more than 148,000 women during a five-year period. Vaccination during pregnancy was not associated with an increased risk of preeclampsia, eclampsia, cesarean section or placental abruption compared to unvaccinated women.

DeSilva M, Vazquez-Benitez G, Nordin JD, Lipkind HS, Romitti PA, et al. Tdap vaccination during pregnancy and microcephaly and other structural birth defects in offspring. JAMA 2016;316(17):1823-1824.
Using the Vaccine Safety DataLink, the authors compared the prevalence of birth defects between infants born to more than 41,000 pregnant women who received Tdap vaccine with unvaccinated women. Vaccination at less than 14 weeks gestation, between 27- and 36-week gestation, or at any time during pregnancy was not associated with an increased risk for microcephaly or any structural defect. 

Hoang, HTT, Leuridan E, Maertens, K, et al. Pertussis vaccination during pregnancy in Vietnam: results of a randomized controlled trial. Vaccine 2016;34:151-159.
In this randomized controlled trial, the authors assessed the safety and efficacy of the pertussis vaccine in pregnant women in Vietnam. Both Tdap and tetanus toxoid vaccines were well tolerated.

Kharbanda EO, Vazquez-Benitez G, Lipkind HS, Klein NP, Cheetham TC, et al. Maternal Tdap vaccination: coverage and acute safety outcomes in the Vaccine Safety Datalink, 2007-2013. Vaccine 2016;34;968-973.
The authors evaluated the risks for adverse events following Tdap vaccination in more than 53,000 pregnant women. They found no increased risk of acute adverse events within 3- or 42-days post-vaccination, including neurologic events, thrombotic events, new onset proteinuria, gestational diabetes, cardiac events, venous thromboembolic events or thrombocytopenia.

Maertens K, Cabore RN, Huygen K, Hens N, Van Damme P, et al. Pertussis vaccination during pregnancy in Belgium: results of a prospective controlled cohort study. Vaccine 2016;34:142-150.
In this prospective, controlled cohort study, the authors assessed the immunogenicity and safety of Tdap immunization during pregnancy. Tdap was generally well-tolerated with mild side effects resolving within 72 hours of vaccine receipt. No reported serious adverse events in the mothers were related to vaccine administration. All reported serious adverse events in infants were common conditions that occur in the neonatal/infant period and were not linked to maternal vaccination.

Petousis-Harris H, Walls T, Watson D, Paynter J, Graham P, et al. Safety of Tdap vaccine in pregnant women: an observational study. BMJ Open 2016;6:e010911.
In this prospective study, the authors followed 800 New Zealand women who received Tdap during the third trimester of pregnancy. Immunization was well-tolerated with no serious adverse events occurring at levels greater than background rates. 

Morgan JL, Baggari SR, McIntire DD, Sheffield JS. Pregnancy outcomes after antepartum tetanus, diphtheria and acellular pertussis vaccination Obstet Gynecol 2015;125(6):1433-1438.
The authors retrospectively evaluated pregnancy outcomes in more than 7,100 women who had or had not received Tdap during pregnancy during a 13-month period. They found no differences in pregnancy outcomes (e.g., stillbirth, major malformations, chorioamnionitis, 5-minute Apgar score, or cord blood pH) or neonatal complications (e.g., ventilation requirement, sepsis, intraventricular hemorrhage, or neonatal death). Additionally, no differences in neonatal outcomes were found between women who had received at least two Tdap vaccines in the past five years with those who had received only a single dose.  

Sukumaran L, McCarthy NL, Kharbanda EO, Weintraub E, Vazquez-Benitez G, et al. Safety of tetanus, diphtheria, and acellular pertussis and influenza vaccinations in pregnancy. Obstet Gynecol 2015;126(5):1069-1074.
The authors evaluated the safety of Tdap and influenza vaccines in 36,000 pregnancies during a seven-year period. Concomitant administration of Tdap and influenza vaccines during pregnancy was not associated with a higher risk of acute adverse outcomes (e.g., fever, limb pain, limb swelling, cellulitis, lymphadenitis, Arthus reaction, or allergy) or birth outcomes (e.g., preterm delivery, low birth weight, small for gestational age) compared to sequential vaccination. No cases of Arthus reaction or Guillain-Barre Syndrome were reported.  

Sukumaran L, McCarthy NL, Kharbanda EO, McNeil MM, Naleway AL, et al. Association of Tdap vaccination with adverse birth outcomes among pregnant women with prior tetanus-containing immunizations. JAMA 2015;314(15):1581-1587.
The authors evaluated the safety of Tdap vaccine in more than 29,000 pregnant women. They found no statistically significant differences in acute adverse events (e.g., fever, allergic reactions or local reactions) or adverse birth outcomes (e.g., preterm delivery, low birth weight, small for gestational age) among women who had received their prior tetanus-containing vaccine less than two years before and two to five years before compared with women who had received a tetanus containing vaccine more than five years earlier. No cases of anaphylaxis, Arthus reaction or Guillain-Barre Syndrome were found following vaccination. 

Donegan K, King B, Byran P. Safety of pertussis vaccination in pregnant women in UK: observational study. BMJ 2014;349:g4219.
The authors conducted an observational cohort study to examine the safety of pertussis vaccination during pregnancy following administration of Repevax®, a low-dose diphtheria, acellular pertussis and inactivated poliomyelitis vaccine. When compared with national historical rates, the authors found no increased risk of stillbirth, maternal or neonatal death, pre-eclampsia, eclampsia, hemorrhage, fetal distress, uterine rupture, placenta or vasa previa, caesarean delivery, low birth weight, or neonatal renal failure. 

Kharbanda EO, Vazquez-Benitez G, Lipkind HS, Klein NP, Cheetham TC, et al. Evaluation of the association of maternal pertussis vaccination with obstetric events and birth outcomes. JAMA 2014;312(18):1897-1904. 
Using the Vaccine Safety Datalink, the authors determined the safety of Tdap vaccination during pregnancy. Vaccination was not associated with increased risks of adverse birth outcomes including preterm delivery, small for gestational age, or hypertensive disorders of pregnancy (e.g., gestational hypertension, preeclampsia, eclampsia, etc.). Although Tdap vaccination during pregnancy was initially associated with a slightly increased risk of chorioamnionitis, chart reviews found that the association between Tdap vaccination at 27- and 36-week gestation was no longer significant.   

Munoz FM, Bond NH, Maccato M, Pinell P, Hammill HA, et al. Safety and immunogenicity of tetanus diphtheria and acellular pertussis (Tdap) immunization during pregnancy in mothers and infants. JAMA 2014;311(17):1760-1769.
In this randomized, double-blind, placebo-controlled clinical trial, the authors evaluated the safety and immunogenicity of Tdap immunization during the third trimester of pregnancy. No Tdap-associated serious adverse events occurred in women or infants. There were no significant differences in the infants’ gestational ages, birth weights, Apgar scores, neonatal examinations, growth, development or complications when comparing those mothers who received Tdap antepartum versus postpartum.

Reviewed by Paul A. Offit, MD on July 18, 2018

Materials in this section are updated as new information and vaccines become available. The Vaccine Education Center staff regularly reviews materials for accuracy.

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