One question that expecting parents get asked a lot is “Boy or Girl?”. Some parents find out as soon as possible and others like to wait until the birth – but this waiting tradition may soon be over, as finding out the sex early in the pregnancy may improve the life chances, animal model studies suggest.
It has been known for a while that a person’s sex can increase some risk factors. For example, cardiovascular disease and type two diabetes do tend to be higher in males than females. This is an area of research that is fascinating scientists, and research is now being conducted on whether this higher risk is also the same in fetuses.
Life-threatening disorders like fetal growth restriction and pre-eclampsia can affect one in 10 pregnancies. Unfortunately, these disorders are very difficult to predict and treat, and there is a forever growing need for more research in identifying these risk factors.
Two mouse studies were conducted to determine these factors. The first was published in the Journal of Biology of Reproduction, and determined that being a male fetus may cause complications.
“We don’t quite know 100 per cent why that is but it might be related to the fact that male babies grow faster within the womb. So it might be that their demands for nutrients and oxygen supplied from the mother through the placenta can easily become limited, so the male baby may not be receiving all that it really wants and needs to grow to its full capacity. It may be that its resilience against stresses or poor conditions in pregnancy may be lower than say, for females, who have got less requirements.” Said Dr Amanda Sferruzzi-Perri, one of the authors of both papers.
The placenta is a remarkable organ and can adapt depending on different cues, including whether the pregnant parent has been eating a sugary, fatty diet; is carrying more than one baby; or, as the study showed, the fetuses’ sex. These placental changes can be seen on multiple levels, such as how the cells form, gene and protein expression, and also the mitochondria.
A second mouse study from the same group was presented in the journal Acta Physiologica earlier this year. It showcased the same male risk factor as before, along with diet-induced maternal obesity as a reason for placenta structure changes that could affect the babies’ growth.
Maternal obesity is a factor known to increase pregnancy complications and abnormal birth weights, and can lead to neurodevelopmental issues and immune disorders in childhood.
“We’re now building more and more evidence of what to measure in the mum in pregnancy like her starting body mass index, her growth, her gestational weight, but also considering fetal sex. Routinely, clinicians do consider sex when they’re looking at ultrasound images, because sex is an important determinant of how the fetus is growing. However, we’ve not really understood before how that might be determined; how that might be interacting with the environment of the mother or the way in which the pregnancy is occurring. So our studies are giving more information to the clinician to provide more informed decisions about how to manage that pregnancy.” Said study author Dr Amanda Sferruzzi-Perri.
“It might be that a woman who has a male baby might need to adopt different lifestyle conditions, than a woman that is carrying a female.”
What may this all this research lead to? A lot of research still needs to be conducted on early pregnancy, but this work may be the basis for designing sex-specific therapies for placental insufficiency and potential fetal growth abnormalities, along with guiding other lifestyle interventions or therapies for maternal diet choices.