Predictors of Plasmodium falciparum Infection in the First Trimester Among Nulliparous Women From Kenya, Zambia, and the Democratic Republic of the Congo

Abstract

Background: Malaria can have deleterious effects early in pregnancy, during placentation. However, malaria testing and treatment are rarely initiated until the second trimester, leaving pregnancies unprotected in the first trimester. To inform potential early intervention approaches, we sought to identify clinical and demographic predictors of first-trimester malaria.

Methods: We prospectively recruited women from sites in the Democratic Republic of the Congo (DRC), Kenya, and Zambia who participated in the ASPIRIN (Aspirin Supplementation for Pregnancy Indicated risk Reduction In Nulliparas) trial. Nulliparous women were tested for first-trimester Plasmodium falciparum infection by quantitative polymerase chain reaction. We evaluated predictors using descriptive statistics.

Results: First-trimester malaria prevalence among 1513 nulliparous pregnant women was 6.3% (95% confidence interval [CI], 3.7%-8.8%] in the Zambian site, 37.8% (95% CI, 34.2%-41.5%) in the Kenyan site, and 62.9% (95% CI, 58.6%-67.2%) in the DRC site. First-trimester malaria was associated with shorter height and younger age in Kenyan women in site-stratified analyses, and with lower educational attainment in analyses combining all 3 sites. No other predictors were identified.

Conclusions: First-trimester malaria prevalence varied by study site in sub-Saharan Africa. The absence of consistent predictors suggests that routine parasite screening in early pregnancy may be needed to mitigate first-trimester malaria in high-prevalence settings.

Keywords: early pregnancy; factors; first-trimester; malaria; predictors; pregnancy; prevalence.

Figure 1.

Map of malaria transmission intensity based on study site. The study locations are located in Nord-Ubangi and Sud-Ubangi provinces in the Democratic Republic of the Congo, in Bungoma, Busia, and Kakamega counties in Kenya, and in Kafue and Chongwe districts in Lusaka province in Zambia. Malaria transmission is modeled from the Plasmodium falciparum parasite rate among children aged 2–10 years (PfPR 2–10) in 2015 and ranges from 0.6 in Nord-Ubangi and Sud-Ubangi provinces in the Democratic Republic of the Congo to 0.0 in Lusaka province in Zambia. Data on the modeled PfPR 2–10 was obtained from the Malaria Atlas Project [26].

Figure 2.

Study population of malaria substudy. The Aspirin Supplementation for Pregnancy Indicated risk Reduction In Nulliparas (ASPIRIN) trial included 3800 women from the Democratic Republic of the Congo (DRC), Kenya, and Zambia. From these women, we took a convenience sample of 1513 women for the malaria substudy: 485 from DRC, 677 from Kenya, and 351 from Zambia.

Figure 3.

Comparisons of predictors for first-trimester malaria among nulliparous women from the DRC (triangles), Kenya (squares), and Zambia (circles) using prevalence differences (A) or prevalence ratios (B). The error bars are 99% CI. Summary estimates were only presented if the I² value was less than 40% and are provided with 99% CI. The vertical gray line is the null value: 0 for prevalence difference in (A), 1 for prevalence ratio in (B). Abbreviations: BMI, body mass index; CI, confidence interval; DRC, Democratic Republic of the Congo; NA, not available; PD, prevalence difference; PR, prevalence ratio; SES, socioeconomic status.