Flu vaccine during pregnancy study adds to evidence

1 March 2017

A new study of Australian woman getting the flu vaccine while pregnant has added to the safety evidence of immunisation during pregnancy.

The Australian 'FluMum' study, published last month in the international journal Vaccine1, retrospectively looked at the birthweights and gestation of babies born to 7126 Australian women over three consecutive years.

The study found no significant difference in birthweight or gestation age at birth of the babies of the 2,429 women who had received the flu vaccine while pregnant and the 4,697 women who had not.  

The Australian study follows a New Zealand study2published last year in the British Medical Journal that followed 793 Kiwi women who received the whooping cough vaccine (the Tdap or acellular pertussis vaccine) during pregnancy (27.9% also received a flu vaccine during pregnancy).  That study monitored injection site reactions, systemic symptoms and serious adverse events (SAE) in the woman during their pregnancy and concluded that vaccination with Tdap in pregnant woman was well tolerated and no SAE likely to be caused by the vaccine.

The Ministry of Health recommends immunisations against influenza and whooping cough during pregnancy to protect both themselves and their child (see quick facts below for more detail). Pregnant women in New Zealand have been able to access fully funded influenza and whooping cough vaccines since 2010 and 2012 respectively.

A New Zealand study into pregnant woman's beliefs about immunisation in pregnancy, released in 2015, said it was not possible to quantify the number of pregnant woman being immunised against the flu or whooping cough because the National Immunisation Register did not include pregnancy as a category.   The study found that most of the women interviewed were confident about immunising their babies and themselves when not pregnant but were less comfortable about immunisation when they were pregnant.  It also conclude that women were more likely to be motivated to immunise against influenza and/or whooping cough if their health professional recommended it as important for protecting their unborn babies.

The most recently released United Kingdom data, where pertussis vaccination is also free, shows pertussis vaccination rates are increasing and averaged 75% of pregnant woman across England between October to December 2016.

More information on immunisation during pregnancy is available at the Ministry of Health  and the Immunisation Advisory Centre


1. McHugh L, Andrews R, Lambert S et al Birth outcomes for Australian mother-infant pairs who received an influenza vaccine during pregnancy, 2012–2014: The FluMum study. Vaccine  Volume 35, Issue 10 2017

2. Petousis-Harris H, Walls T, Watson D, et al. Safety of Tdap vaccine in pregnant women: an observational study. BMJ Open 2016;6:e010911. doi:10.1136/bmjopen-2015-010911


  • New Zealand research shows that healthy pregnant woman are nearly five times more likely to be hospitalised than non-pregnant woman due to influenza complications
  • Women who catch influenza during pregnancy have higher rates of general pregnancy complications, including premature birth, stillbirth and babies who are small for gestational age
  • An immunised pregnant woman passes flu immunity onto their child in the womb reducing the chances of a newborn getting the flu.
  • Immunity to whooping cough decreases over time so adults can catch whooping cough even if they have been immunised in past or previously had the disease.
  • A woman immunised against pertussis (whooping cough) while pregnant can pass on immunity to their baby until they are old enough to be immunised.
  • Whooping cough outbreaks occur every 3-5 years with New Zealand's most recent outbreak being from August 2011-December 2013 with about 11,000 cases notified and three deaths of young children.

Source; Ministry of Health

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