The changing panorama of late fetal death in Sweden between 1984 and 1991.

BACKGROUND: During the last decade there has been a significant reduction in early neonatal mortality. The rate of late fetal death, however, has not changed significantly despite improvements in antenatal care. This study evaluated the years 1984 and 1991 as to possible changes in well known risk factors for late fetal death. METHODS: We studied all single births during 1984 and 1991 recorded in the Swedish Medical Birth Register. In 1984, there were 94,270 births; of these, 381 were late fetal deaths. In 1991, there were 124,201 births and 464 late fetal deaths. The risk factors analyzed included maternal age, parity, smoking, birth weight, birth weight deviation, plurality, hypertension, diabetes, placental complications and previous late fetal death. Some of these variables were assessed in a cohort design and others in a case-control design. RESULTS: The small reduction in the late fetal death rate between 1984 and 1991 (4.0/1000 vs. 3.7/1000 births) may be explained by changes in maternal age and parity. However, it seems more likely that changes have occurred in the various risk factors, but the net result did not affect the late fetal death rate. Although the number of mothers who smoked decreased from 30% to 24%, this habit increased as a risk factor, especially when it was >=10 cig/day (odds ratio 1.24 vs. 1.97). Infants <2500g showed a significant decrease in the risk of late fetal death. No significant change in the latter risk was found among infants small for gestational age. CONCLUSIONS: Demographic changes may entirely explain the small decrease in late fetal death rate between 1984 and 1991. Despite all the improvements in the care of pregnant women between these years, the net gain, in terms of a decreasing number of late fetal deaths, is small, which most likely is due to shifts in the fetal death risks between the risk factors. Further significant decreases in the number of late fetal deaths may be difficult to obtain through improvements in the Maternal Health Care Service.