New research suggests that maternal stress during pregnancy can affect fetal development. But in what ways?
Pregnancy is often a happy period, of course, but it also involves profound physical and psychological transformations for the mother, sometimes sources of stress. But what are the impacts of this stress on the development of the baby? Two new studies have looked into the question. It appears that prenatal stress seems to affect the development of the brain of the fetus, increase the risk of premature delivery, and orient the sex of the baby.
The first is signed by King's College London. Researchers have focused on the impact of maternal stress on fetal brain development. To do this, they examined 251 babies born prematurely in the UK, focusing on white matter development. The mothers concerned, for their part, completed a questionnaire in order to assess their level of stress during pregnancy.
The researchers then found that in the most stressed mothers during pregnancy and the period before birth, the white matter was reduced in babies. At this point, the consequences of this abnormal white matter development are unclear. But there are potential links to future problems with anxiety, depression or schizophrenia.
The second study is from Columbia University, USA. The objective of this research was to categorize different types of prenatal stress (no particular stress, mental stress and physical stress) and to determine their influence on birth. Just over 180 women were followed throughout their pregnancy.
Several things were revealed. On the one hand, that high levels of physical and psychological stress during pregnancy increase the chances of a girl being born . Indeed, there are on average about 105 births of boys for every 100 births of girls. But under physical and psychological stress, the boy/girl ratio drops to 4:9, and 2:3, respectively.
“Other researchers have observed this phenomenon after social upheaval. Such as the 9/11 terrorist attacks in New York, following which the relative number of male births declined” , underlines Catherine Monk, main author of this study.
On the other hand, it has emerged that significant physical stress during pregnancy promotes the risk of premature delivery . The researchers also observed a decreased heart rate fetal . Psychologically stressed women, on the other hand, seem to suffer from more birth complications.
Note that these two studies make connections, but do not focus on possible explanations. However, Monk points out that animal research has already suggested that stress hormones – such as cortisol – can directly affect fetal development.
“Stress can also affect the mother's immune system, leading to changes that affect the neurological and behavioral development of the fetus , she adds. What is clear in our study is that the mental and physical health of the mother matters. Not only for the mother, but also for her future child” .
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