Body mass index and labor outcome associated with the level of amniotic fluid lactate. A cross-sectional study of women with labor dystocia

Abstract

Introduction Obesity is a globally growing problem. Labor dystocia is associated with obstetric complications, especially among obese pregnant women. Previous studies have shown an association between the level of lactate produced by uterine myocytes during contractions and the level of lactate in the amniotic fluid (AFL). A relationship between a high level of AFL and labor dystocia has also been demonstrated. However, it is still unknown whether the observation applies to all women with labor dystocia, regardless of body mass index (BMI). Aims: This study investigated whether there was any difference in the level of AFL in the three BMI groups and whether there was a difference in labor outcomes between high and low AFL in the different groups. Materials and Methods This cross-sectional study included 1683 women from three different countries. Healthy nulliparous women in active labor were included, and they were grouped according to BMI as normal weighted (<25), overweight (≥25–29), and obese (≥30), respectively. AFL was categorized as high (≥10.1 mmol/l) and low (<10.1 mmol/l). The main outcome was the frequency of cesarean section. Results No difference in AFL levels was found between the three BMI groups at delivery (mean values of 8.2 vs. 8.3 vs. 8.4 mmol/l, p = .3). Obese women with high AFL had a higher frequency of cesarean section than normal-weighted women (16.2 vs. 20.7 vs. 29.2%). Other risk factors associated with cesarean section varied among the different BMI groups. Conclusions This study showed no difference in the mean level of AFL between women with different BMIs. Further, high AFL was associated with a higher frequency of cesarean section in all three BMI groups, suggesting that the level of AFL can in the future be used as a predictor of labor outcome among women with labor dystocia despite their BMI.