Stillborns Likely After Small Babies 

JEFF DONN / AP 19feb04

[Abstract below]

BOSTON - Women who give birth to small babies — whether prematurely or not — are more likely to have stillborns 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.

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.

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.

Stillbirth in 2nd pregnancy (rate per 1,000 births)

			Length of first pregnancy                .
Outcome of first	37 weeks	32 weeks to	Less than
       pregnancy	or more		36 weeks	32 weeks

  Infant was not	2.4		2.7		6.0
   small for age

  Infant was not	4.8		9.5		19.0
   small for age

Previous Preterm and Small-for-Gestational-Age Births and the 
Subsequent Risk of Stillbirth 

New England Journal of Medicine v.350, n.8 19feb04

Pamela J. Surkan, M.S., Olof Stephansson, M.D., Ph.D., Paul W. Dickman, Ph.D., and Sven Cnattingius, M.D., Ph.D.

ABSTRACT

Background Some causes of stillbirth may also lead to fetuses that are small for gestational age (have a low birth weight with respect to their gestational age) or are delivered preterm (before 37 weeks of gestation). It is not known whether the birth of a previous small-for-gestational-age or preterm infant increases the subsequent risk of stillbirth.

Methods We assessed the associations between previous adverse outcomes of pregnancy and the risk of stillbirth in a nationwide Swedish study of 410,021 women who delivered first and second consecutive singleton infants between 1983 and 1997. There were 1842 and 1062 stillbirths during the first and second pregnancies, respectively.

Results As compared with women whose first infant was born at term (37 weeks of gestation or more) and was not small for gestational age, women whose first infant was born at term or preterm and was small for gestational age had an increased risk of stillbirth during their second pregnancy. The odds ratios for subsequent stillbirth, after adjustment for covariates known to be associated with an increased risk of stillbirth, were 2.1 (95 percent confidence interval, 1.6 to 2.8) among women with a first infant who was born at term and was small for gestational age, 3.4 (95 percent confidence interval, 2.1 to 5.6) among women with a first infant who was moderately (32 to 36 weeks of gestation) preterm and small for gestational age, and 5.0 (95 percent confidence interval, 2.5 to 9.8) among women with a first infant who was very (before 32 weeks of gestation) preterm and was small for gestational age. The odds ratio for subsequent stillbirth among women with a first stillborn infant was 2.5 (95 percent confidence interval, 1.4 to 4.7), as compared with women whose first infant was not stillborn. The rates of stillbirth in second pregnancies ranged from 2.4 per 1000 births among women whose first infant was born at term and was not small for gestational age to 19.0 per 1000 births among women whose first child was very preterm and was small for gestational age.

Conclusions Delivery of a previous small-for-gestational-age infant is an important predictor of the subsequent risk of stillbirth, particularly if the infant was delivered preterm.

Source Information

From the Departments of Medical Epidemiology and Biostatistics (P.J.S., O.S., P.W.D., S.C.) and Women's and Children's Health (O.S.), Karolinska Institutet, Stockholm, Sweden; and the Department of Maternal and Child Health, Harvard School of Public Health, Boston (P.J.S.).