How will the vaccines affect my baby?

Key facts

  • When you have a vaccine during pregnancy, the antibodies that your immune system produces will cross the placenta to give your baby protection against the disease, too. 

  • Research shows that the risk of pregnancy complications does not increase for women who have been vaccinated during pregnancy.

Last updated on 8 May 2023.

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Overview

Vaccines work by triggering your immune system to produce antibodies that recognise and get rid of certain diseases and infections. When you are pregnant, those antibodies cross the placenta to give your baby protection, too.

How does the vaccine work?

Vaccines work by training your body’s immune system to recognise and get rid of germs that cause serious illness. They contain ‘antigens’ which are tiny fragments of the virus or bacteria that causes the disease they are targeting. When your immune system detects these antigens, it produces antibodies to fight them and get rid of them.

People usually start producing antibodies around one or two weeks after they have a vaccine. When you’re pregnant it can take a bit longer.

How will the vaccine affect my baby?

When you have a vaccine during pregnancy, the antibodies that your immune system produces will cross the placenta to give your baby protection against the disease, too. The antibodies can also be passed on through your breastmilk.

How are the vaccines for pregnant women different from other vaccines?

In Australia, only ‘inactivated’ vaccines are recommended for women during pregnancy.  

All vaccines contain ‘antigens’ which are fragments of the bacteria or virus that causes the disease the vaccine is targeting. The antigens in the vaccines recommended for pregnant women are ‘inactivated’ meaning that the bacteria or viruses they are made from have been killed before being introduced to the vaccine. Inactivated antigens cannot reproduce themselves or cause disease.

‘Live’ vaccines contain ‘live’ antigens and should not be given to women during pregnancy.

Are there any risks?

Both the influenza vaccine and the whooping cough (pertussis) vaccine are safe for pregnant women and their babies. Research shows that the risk of pregnancy complications does not increase for women who have been vaccinated during pregnancy, and their babies are not at any greater risk of health issues during pregnancy or at birth.

The hepatitis B vaccine recommended for newborn babies is safe. Research shows that the risks of complications such as Sudden Unexpected Death in Infancy (SUDI) are no higher for babies who have had the hepatitis B vaccine than they are in babies who have not been vaccinated.

The influenza vaccine is safe for pregnant women and for their babies. Research tells us that being vaccinated against influenza during pregnancy does not increase the risk of adverse pregnancy outcomes such as stillbirth, premature delivery, or birth defects1-4. Specifically:

  • There were lower rates of stillbirth among women who had an influenza vaccine in pregnancy compared to those women who did not get an influenza vaccine in pregnancy 1-3.
  • There was no difference in the length of pregnancy (gestation period) for babies born to mothers who had the influenza vaccine in pregnancy and those who didn’t1, 4.
  • There was no difference in the rates of birth defects among women who had an influenza vaccine in pregnancy compared to those women who did not get a influenza vaccine in pregnancy2.

The whooping cough vaccine is safe for pregnant women and for their babies. Research tells us that being vaccinated against whooping cough during pregnancy does not increase the risk of adverse pregnancy outcomes5. Specifically, a review of many studies5 confirmed that for mothers vaccinated against whooping cough during pregnancy there was:

  • no increase in the risk of preterm birth (birth under 37 weeks of gestation)
  • no increase in the risk of stillbirth or neonatal death (death during the first 28 days of life)
  • no increase in the risk of babies that were small for gestational age
  • no increase in the risk of low birth weight (less than 2.5kg)
  • and no increase in the risk of birth defects.

The hepatitis B vaccine is safe for newborns.

  • There is no evidence that the dose given at birth affects a mother and baby’s ability to breastfeed6,7.
  • There is no evidence that the birth dose is associated with Sudden Unexpected Death in Infancy (SUDI) or Sudden Infant Death Syndrome (SIDS)8.
  • There is no evidence that the birth dose is associated with autism9.
  • The birth dose is not associated with an increased risk of fever6,7.
  • The birth dose is not associated with an increased need for medical investigations into serious infection or sepsis in newborns6,7.

Most babies who have the hepatitis B vaccine at birth have only very mild reactions such as some redness, soreness or swelling at the spot where the needle went in6. 

Could my baby and I catch the disease from the vaccine?

No. There is no risk that either you or your baby could catch the disease from the influenza and whooping cough vaccines recommended for women during pregnancy, or the hepatitis B vaccine recommended for newborns, because they do not contain any live ‘antigens’. (Antigens are fragments of the bacteria or virus that causes the disease the vaccine is targeting, and are the most important ingredient in the vaccine.) Inactivated antigens cannot reproduce themselves or cause disease.  

In Australia, only ‘inactivated’ vaccines are recommended for women during pregnancy. ‘Live’ vaccines contain ‘live’ antigens and should not be given to women during pregnancy.

The development of this content was led by the Murdoch Children's Research Institute for the MumBubVax website (now archived).


  1. Fell DB, Platt RW, Lanes A, Wilson K, Kaufman JS, Basso O, et al. Fetal death and preterm birth associated with maternal influenza vaccination: systematic review. BJOG. 2015;122(1):17-26.
  2. McMillan M, Porritt K, Kralik D, Costi L, Marshall H. Influenza vaccination during pregnancy: a systematic review of fetal death, spontaneous abortion, and congenital malformation safety outcomes. Vaccine. 2015;33(18):2108-17.
  3. Regan AK, Moore HC, de Klerk N, Omer SB, Shellam G, Mak DB, et al. Seasonal trivalent influenza vaccination during pregnancy and the incidence of stillbirth: population-based retrospective cohort study. Clinical infectious diseases. 2016;62(10):1221-7.
  4. McHugh L, Andrews RM, Lambert SB, Viney KA, Wood N, Perrett KP, et al. Birth outcomes for Australian mother-infant pairs who received an influenza vaccine during pregnancy, 2012-2014: The FluMum study. Vaccine. 2017;35(10):1403-9.
  5. McMillan M, Clarke M, Parrella A, Fell DB, Amirthalingam G, Marshall HS. Safety of tetanus, diphtheria, and pertussis vaccination during pregnancy: a systematic review. Obstet Gynecol. 2017 Mar;129(3):560-573.
  6. Lewis E, Shinefield HR, Woodruff BA, Black SB, Destefano F, Chen RT, et al. Safety of neonatal hepatitis B vaccine administration. Pediatric Infectious Disease Journal.2001;20:1049- 54.
  7. Eriksen EM, Perlman JA, Miller A, Marcy SM, Lee H, Vadheim C, et al. Lack of association between hepatitis B birth immunization and neonatal death: a population-based study from the Vaccine Safety Datalink Project. Pediatric Infectious Disease Journal. 2004;23:656-61.
  8. Institute of Medicine (US) Immunization Safety Review Committee. Immunization Safety Review: Vaccinations and Sudden Unexpected Death in Infancy. Washington, DC: National Academies Press, 2003.
  9. Taylor LE, Swerdfeger AL, Eslick GD. Vaccines are not associated with autism: An evidence-based meta-analysis of case-control and cohort studies. Vaccine. 2014;32(29):3623-9.