Malaria Infections and Placental Blood Flow: A Doppler Ultrasound Study From a Preconception Cohort in Benin

Abstract

Background: Malaria in pregnancy (MiP) has been associated with fetal growth restriction, the underlying pathogenic mechanisms of which remain poorly understood. Malaria in pregnancy is suspected to induce abnormalities in placental vascularization, leading to impaired placental development. Our study evaluated MIP's effect on uterine artery (UtA) and umbilical artery (UA) blood flow.

Methods: The analysis included 253 Beninese women followed throughout pregnancy and screened monthly for submicroscopic and microscopic malaria. Uterine artery Doppler measurement was performed once between 21 and 25 weeks' gestation (wg), and UA Doppler measurement was performed 1-3 times from 28 wg. Linear and logistic regression models were used to assess the effect of malaria infections on UtA Doppler indicators (pulsatility index and presence of a notch), whereas a logistic mixed model was used to assess the association between malaria infections and abnormal UA Doppler (defined as Z-score ≥2 standard deviation or absent/reversed UA end-diastolic flow).

Results: Primigravidae represented 7.5% of the study population; 42.3% of women had at least 1 microscopic infection during pregnancy, and 29.6% had at least 1 submicroscopic infection (and no microscopic infection). Both microscopic and submicroscopic infections before Doppler measurement were associated with the presence of a notch (adjusted odds ratio [aOR] 4.5, 95% confidence interval [CI] = 1.2-16.3 and aOR 3.3, 95% CI = .9-11.9, respectively). No associations were found between malaria before the Doppler measurement and abnormal UA Doppler.

Conclusions: Malaria infections in the first half of pregnancy impair placental blood flow. This highlights the need to prevent malaria from the very beginning of pregnancy.

Keywords: Africa; Doppler measurements; malaria in pregnancy; umbilical artery; uterine artery.

Figure 1.

Flowchart diagram of the study population, REtard de Croissance Intra-uterin et PALudisme (RECIPAL) cohort, southern Benin, 2014–2017. *Study completion: 24-month follow up without pregnancy from enrollment. ^$All uterine artery (UtA) Dopplers and a random subsample of umbilical artery (UA) Dopplers were validated a posteriori by an experienced obstetrician-gynecologist. ¹For UtA analysis, 78 women without UtA Doppler (69 noninterpretable UtA Doppler and 9 with UA Doppler only) were excluded.² For UA analysis, 3 women without UA Doppler (3 with validated UtA Doppler only) were excluded.