Stress experienced by a woman during pregnancy may have an effect on her unborn child, most likely mediated by the transfer of stress hormones across the placenta.
Research published in May’s edition of Clinical Endocrinology shows that from 17 weeks of age, the amount of stress hormone in the amniotic fluid surrounding the fetus is positively related to that in the mother’s blood. This is the first report of this relationship noted at such an early stage in pregnancy.
Stress hormones are pumped into our blood when we become anxious. These hormones are good in the short term because they help our bodies deal with the present stressful situation. But if we are stressed for a long time they can affect our health including making us tired, depressed and more prone to illness. Although we know stress during pregnancy affects the unborn child, little is understood about the mechanisms behind this or when in development the child is most susceptible to these effects.
Researchers led by Prof Vivette Glover at Imperial College London and Dr Pampa Sarkar at Wexham Park Hospital Berkshire examined the relationship between the stress hormones in the mother’s blood and stress hormones present in the amniotic fluid around the baby in the womb. They studied 267 women, taking a blood sample from the mother and a sample from the amniotic fluid surrounding the baby. They then measured the levels of a stress hormone called cortisol present in both samples. At gestational age of 17 weeks or greater, they found that the higher the cortisol levels in the mother’s blood, the greater was the level of cortisol in the amniotic fluid. Amniotic fluid is predominantly produced by the fetus, and reflects the exposure of the fetus to various substances including hormones.