Risk of stillbirth at term and optimum timing of delivery in uncomplicated south Asian singleton pregnancies

Abstract

OBJECTIVES: Aims of this study were to compare the perinatal mortality rate and the prospective risk of stillbirth for each given gestational age and to ascertain whether it is safe to continue the pregnancy beyond 40 weeks of gestational age and induce labour at 41 weeks in low risk singleton pregnancies. METHODS: This was a retrospective study. The perinatal mortality and prospective risk were calculated per 1000 total births and 1000 ongoing pregnancies respectively in well dated singleton pregnancies. 38+0 to 39+6 gestational age was taken as the reference. RESULTS: A total of 12,595 deliveries after 28 weeks of gestation were included. The risk of stillbirth at 38+0 to 39+6 weeks was 1.43 (95% CI, 0.9 to 2.4) per 1000 on going pregnancies. The perinatal mortality rate at 38+0 to 39+6 weeks was 2.9 (95% CI, 1.9 to 4.5) per 1000 total births. The perinatal mortality rate decreased throughout gestation and it was lowest at 40+0 - 41+6. In contrast, risk of stillbirth increased with advancing gestation and peaked at 40+0 - 41+6 (2.57, 95% CI, 1.4 to 4.7). However, risk of stillbirth at 40+0 - 41+6 was not statistically different from 38+0 to 39+6 (OR 1.79, 95% CI, 0.80 to 3.98). To prevent one stillbirth, 886 pregnancies should be induced at 38+0 to 39+6. CONCLUSIONS: Risk of stillbirth is more informative than perinatal mortality at term. Frequent antenatal fetal surveillance should be adopted towards term in order to identify high risk pregnancies. Elective delivery before 40 weeks in low risk pregnancies is not justified.