Severe pre-pregnancy stress tied to preterm birth
NEW YORK (Reuters Health) - Women who suffer the stress of a death or serious illness of a loved one shortly before becoming pregnant may have an increased risk of premature delivery, a large study suggests.
The findings, published in the journal Human Reproduction, add to evidence that severe stress can contribute to pregnancy complications, including low birthweight and stillbirth.
Researchers found that among more than 1 million Danish women who gave birth over 24 years, those who'd dealt with a death or serious illness in the family shortly before pregnancy were more likely to deliver prematurely.
Overall, women who'd experienced such stress in the six months before pregnancy were 16 percent more likely to have a preterm birth. When it was one of their children who had died or become ill, the odds of premature delivery increased by 23 percent, while the risk of a very early delivery went up by 59 percent.
It's possible that highly stressful experiences like these have hormonal effects that contribute to preterm birth in some women, according to lead researcher Dr. Ali Khashan of the University of Manchester in the UK.
Severe stress before or around the time of conception, Khashan told Reuters Health, may alter a woman's levels of the stress hormone cortisol and corticotropin-releasing hormone (CRH), which is involved in embryo implantation and the formation of the placenta.
CRH levels normally rise before a woman gives birth, and "precocious elevations" in the hormone have been found in women who deliver prematurely, Khashan noted.
Still, most women who go through severe stress before pregnancy will not deliver prematurely. In this study, only 4.5 percent of these women had a preterm delivery (before the 37th week of pregnancy).
"Our work shows that very severe stress has a subtle effect on preterm birth," co-researcher Dr. Louise Kenny, a senior lecturer at University College Cork, in Ireland, told Reuters Health.
"We needed to look at a large population to uncover this effect," Kenny explained. "This means that for an individual woman, the actual risk of preterm delivery related to severe stress is very small indeed."
As always, the researcher noted, all women who are pregnant or planning a pregnancy should strive for a healthy lifestyle and follow their doctors' advice.
SOURCE: Human Reproduction, online December 3, 2008.