The risk of a pregnant woman developing gestational diabetes – hyperglycemia during the time nearing childbirth, as a result of less insulin from pancreatic beta-cell dysfunction – is affected by the sex of the fetus, suggests a 4-year study of hundreds of thousands of women.

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Would knowing the sex of your baby had an influence on maternal health change your position on preferring to be surprised at the birth?

Published in the Journal of Clinical Endocrinology & Metabolism, one of its authors, Dr. Baiju Shah of the Sunnybrook Health Sciences Centre at the University of Toronto, Canada, gives his conclusion:

“Our findings suggest a male fetus leads to greater pregnancy-associated metabolic changes than a female fetus does.”

Dr. Shah explains that gestational diabetes is thought to occur because of a combination of underlying metabolic abnormalities in the mother and temporary metabolic changes that take place during pregnancy. He adds:

“Public health programs often focus on how a pregnant mother’s health, behavior and physiology can impact the health of her baby.”

Dr. Shah, also with the Institute for Clinical Evaluative Sciences in Toronto, continues:

This study, however, suggests that the baby can help us better understand the health of the mother, and can help us predict her risks for future diseases.”

The authors discuss in the paper how the sex of the baby and the woman’s glucose tolerance status in pregnancy “can together provide insight into a woman’s diabetic risk after delivery” – and in a subsequent pregnancy, too.

Nearly 643,000 women who delivered their first child between April 2000 and March 2010 were studied via insurance records in the retrospective cohort study, which included only births to a single baby.

In addition to the finding that pregnancy with boys was associated with a higher likelihood of gestational diabetes, if the condition did, regardless, develop during a female pregnancy, the mothers went on to show a greater risk of type 2 diabetes after the pregnancy.

Dr. Shah proposes that these women had a greater underlying metabolic susceptibility to gestational diabetes, “even without the added impact” suggested by the study of a developing male fetus.

The study is not the first – but is the largest – to find a link with fetal sex for pregnancy-related diabetes, say the authors. The population-based cohort consisted of the entire maternal population of Ontario.

The study ends with the note that its findings mean fetal sex “emerges as a previously unrecognized factor associated with the natural history of maternal diabetic risk both after delivery and in a subsequent pregnancy.” That conclusion follows this summary of the researchers’ findings on gestational diabetes mellitus (GDM):

  1. In women with GDM, delivery of a girl is associated with a higher risk of early progression to type 2 diabetes, compared with having a boy
  2. Carrying a male fetus is associated with an increased risk of GDM overall but does not increase the likelihood of its recurrence in a second pregnancy
  3. In women with a non-GDM first pregnancy, the increased risk of GDM associated with a male fetus in a subsequent pregnancy is particularly evident in those who previously delivered a girl.

Fetal effects on pregnant women are rarely brought to our attention, as referred to by Dr. Shah. Findings about the reverse, however – maternal effects on fetuses – are regularly reported, perhaps unsurprisingly, given numerous maternal variables. On Tuesday, for example, study results linked maternal obesity to reduced immunity in newborns.