Discordant dating of pregnancy by LMP and ultrasound and its implications in perinatal statistics

High perinatal mortality in India may be caused by inaccurate dating of pregnancy resulting from suboptimal uptake of antenatal care and ultrasound services during pregnancy.

To determine the discrepancy in the last menstrual period (LMP) assigned expected date of delivery (EDD) and ultrasound assigned EDD in pregnant women in a rural district of central India.

Data from an ongoing cross-sectional screening program providing fetal radiology imaging in Guna district of Madhya Pradesh from 2012-2019 was analyzed for recall of LMP and discordance between LMP and ultrasound assigned EDD. The discrepancy was present when EDD assigned by ultrasound differed by 3 or more days at gestational ages less than 8⁺⁶ weeks, 5-7 days at gestational ages 8⁺⁶ weeks till 14 weeks, and 7-10 days at gestational ages 14-20 weeks.

The program screened 14,701 pregnant women of which 4,683 (31.86%, 95% CI: 31.11, 32.61) could not recall LMP. EDD assigned by LMP and ultrasound matched in 7,035 (70.22%, 95% CI: 69.32, 71.12) of the remaining 10,018 pregnant women. EDD was overestimated by LMP for 26.06% (95% CI: 25.21, 26.93) women; these foetuses were at risk of being misclassified as a term fetus. In 2018, the project had no maternal deaths, infant mortality rate of 24.7, low birth weight rate of 9.69%, and 100% antenatal coverage.

Accurate dating of pregnancy and systematic follow-up integrating radiology imaging and obstetrics care for appropriate risk-based management of pregnant women can significantly improve perinatal statistics of India.