Women who give birth to small babies — whether prematurely or not — are more likely to have a stillborn during their next pregnancy, a study found.
The Swedish study, published in Thursday’s New England Journal of Medicine, suggests that the same causes may underlie both stillbirths and stunted growth in fetuses.
However, since so little can be done about many growth problems, the study is not expected to bring about any big changes in obstetrics.
The researchers used a national registry with 410,021 women who had two consecutive pregnancies resulting in live or stillbirths.
Women who had small but full-term babies ran double the risk of a stillbirth in their next pregnancy.
Small babies, higher risk
Preterm newborns raised the later risk of a stillbirth only if they were also small for their fetal age. The risk of a later stillbirth was five times higher if the newborn was both very small for its fetal age and very early in its delivery — before 32 weeks.
Newborns who were in the bottom 2.5 percent in size at a given stage of development were considered small for their fetal age.
Though small newborns heightened the risk of later stillbirths, the overall rate of stillbirths for the second pregnancy was low at 2.6 per 1,000 births. Even in the highest risk group, there were only 19 stillbirths per 1,000 births.
Infections, respiratory problems, congenital defects and other factors can cause stillbirths. This study did not consider the causes of the stillbirths, so it is not clear exactly which ones stillbirths and small-for-fetal-age births may share.
A probe called Doppler ultrasound can show blood flow in a fetus and point to possible nutritional problems and stunted growth at an early stage of development.
Study raises questions
However, the study leaves doctors in a bind over whether to induce delivery of very preterm babies with serious growth problems. An early delivery could save the child from stillbirth but put it at risk by such an early birth.
“If you have a baby that may be suffering 14 weeks prior to delivery, how to you deal with this one? I don’t think anybody knows,” said one of the researchers, Dr. Sven Cnattingius of the Karolinska Institute in Stockholm.
However, pediatrician Dr. Mark Klebanoff, a researcher at the National Institutes of Health who co-wrote an accompanying commentary, said the study should at least help doctors and women judge the magnitude of risk for stillbirths.