The newest man in your life could be causing you problems before he is even born.
That's the message to parents following a University of Adelaide study, which found pregnant mothers carrying boys were more likely to suffer birth complications.
The study investigated data of more than 574,000 births in South Australia between 1981 and 2011 and is the first population-based study of its kind in Australia to confirm differences in birth outcomes for boys and girls.
"Sex is obviously determined at conception but if you think about it there are a lot of things that we know that help to decrease these complications," she said.
Professor Roberts said almost 50 per cent of pregnancies in Australia were unplanned and parents could help reduce health risks by learning how to prepare.
"We would want mothers to maintain a good quality diet, exercise regime, abstaining from alcohol, cigarettes and illicit drugs - that also goes across to men as well," she said.
"The sex of the baby is a contributing factor to these adverse outcomes but you can improve pregnancy outcomes by improving your own health and that of your partner.
"Potentially we should be devising new therapeutics that will be tailored to whether the foetus is male or female."
The study found:
- Boys are more likely to be born spontaneously pre-term. Boys show a 27 per cent higher risk for a pre-term birth between 20-24 weeks' gestation, 24 per cent higher risk between 30-33 weeks, and 17 per cent higher risk for pre-term birth between 34-36 weeks.
- Mothers carrying boys are 4 per cent more likely to suffer gestational diabetes.
- Mothers carrying boys are 7.5 per cent more likely to suffer pre-eclampsia at term.
- Pregnant women carrying a girl have a 22 per cent higher risk for early onset pre-eclampsia requiring a pre-term delivery.
Professor Roberts and her colleagues have previously published on sex differences in the expression of 142 genes in the placenta from normal pregnancies.
"We know that pregnancy complications are often something not quite right in the placenta early in the pregnancy," she said.
"The sex differences we have observed in gene expression between normal male and female placentas are likely to be a major contributing factor to sex differences outcomes."
"The next step is to understand the consequence of these differences and how they influence the path to pregnancy complications."
The research was conducted by the Robinson Research Institute and was funded by the National Health and Medical Research Council (NHMRC).
Article: Sexual Dimorphism in Adverse Pregnancy Outcomes - A Retrospective Australian Population Study 1981-2011, Petra E. Verburg, Graeme Tucker, Wendy Scheil, Jan Jaap H. M. Erwich, Gus A. Dekker, Claire Trelford Roberts, PLOS ONE, doi: 10.1371/journal.pone.0158807, published 11 July 2016.