Background Effective antenatal care (ANC) requires high quality longitudinal services to provide a health benefit to mothers and newborns. Few studies have assessed the quality of care across the continuum of pregnancy or its impact on outcomes in lower income countries with high perinatal mortality.

Methods and findings We conducted a prospective study in eight rural and urban sites in Ethiopia, India, Kenya, and South Africa that followed women from their first ANC visit until childbirth. We created a longitudinal ANC quality score that included repeated interventions in pregnancy and described ANC quality trajectories by gestational age. We also assessed associations between longitudinal ANC quality – categorized into three groups: low (0–50% of recommended care received), moderate (51%–74.9%), and higher quality (75%–100%) – and intrapartum complications and poor postpartum health using logistic regression models adjusted for sites, demographics, and baseline risk factors.

A total of 3,602 women were included in the present study. On average, women had a total of 4.3 ANC visits. Average longitudinal ANC quality was 46% in Ethiopia, 57% in Kenya, 74% in India, and 79% in South Africa, with reference to national guidelines. Only 20 of 3,602 women (0.6%) received all recommended care items. Few women received the recommended three urine and blood tests in pregnancy: only 5%–11% in Kenya and 13%–21% in Ethiopia. Timely ultrasounds (before 24 weeks’ gestation) ranged from 12% in Kenya to 54% in Ethiopia. While ANC quality remained relatively stable over the course of pregnancy in India and South Africa, it declined as pregnancy progressed in Ethiopia and Kenya. During the third trimester, only around half of women in these two countries received a blood test, and just one third received a urine test. In adjusted regression models, the odds of intrapartum complications and poor postpartum health were, respectively, 44% and 55% lower among women who received higher longitudinal ANC quality compared to those who received low quality ANC (adjusted odds ratio (aOR) 0.56, 95% CI 0.34, 0.92, and aOR 0.45, 95% CI 0.29-0.70)

Conclusions We found important gaps in longitudinal ANC quality and poor provision of recommended anemia and gestational diabetes clinical protocols in pregnancy. These were associated with worse health outcomes. One area of concern is the decline in quality during the third trimester in two of the countries – a time when complications frequently arise that can be mitigated with quality care. Policymakers and health system managers should track longitudinal care quality during pregnancy to identify and redress persistent gaps in maternal and child health care quality. Global and national guidelines and medical education should also reinforce the importance of late-pregnancy surveillance.

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