Maternal anaemia and polycythaemia during pregnancy and risk of inappropriate birth weight for gestational age babies: a retrospective cohort study in the northern belt of Ghana.

Background: Small for gestational age (SGA) and large for gestational age (LGA) births are topical issues due to their devastating effects on the life course and are also accountable for neonatal mortalities and long-term morbidities.

Objective: We tested the hypothesis that abnormal haemoglobin levels in each trimester of pregnancy will increase the risk of SGA and LGA deliveries in Northern Ghana.

Design: A retrospective cohort study was conducted from April to July 2020.

Settings And Participants: 422 postpartum mothers who had delivered in the last 6-8 weeks before their interview dates were recruited through a systematic random sampling technique from five primary and public health facilities in Northern Ghana.

Primary Measures: Using the INTERGROWTH-21st standard, SGA and LGA births were obtained. Haemoglobin levels from antenatal records were analysed to determine their effect on SGA and LGA births by employing multinomial logistic regression after adjusting for sociodemographic and obstetric factors at a significance level of α=0.05.

Results: Prevalence of anaemia in the first, second and third trimesters of pregnancy was 63.5%, 71.3% and 45.3%, respectively, and that of polycythaemia in the corresponding trimesters of pregnancy was 5.9%, 3.6% and 1.7%. About 8.8% and 9.2% of the women delivered SGA and LGA babies, respectively. After adjusting for confounders, anaemic mothers in the third trimester of pregnancy had an increased risk of having SGA births (adjusted OR, aOR 5.56; 95% CI 1.65 to 48.1; p<0.001). Mothers with polycythaemia in the first, second and third trimesters of pregnancy were 93% (aOR 0.07; 95% CI 0.01 to 0.46; p=0.040), 85% (aOR 0.15; 95% CI 0.08 to 0.64; p<0.001) and 88% (aOR 0.12; 95% CI 0.07 to 0.15; p=0.001) protected from having SGA births, respectively. Interestingly, anaemia and polycythaemia across all trimesters of pregnancy were not statistically significant with LGA births.

Conclusion: Anaemia during pregnancy increased from the first to the second trimester and subsequently decreased in the third trimester while polycythaemia consistently decreased from the first to the third trimester. LGA babies were more predominant compared with SGA babies. While anaemia in the third trimester of pregnancy increased the risk of SGA births, polycythaemia across the trimesters offered significant protection. Healthcare providers and stakeholders should target pressing interventions for anaemia reduction throughout pregnancy, especially during the third trimester to achieve healthy birth outcomes.