Department of Global Health Systems and Development, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA 70112, USA.
Lancet Infect Dis. 2012 Dec;12(12):942-9. doi: 10.1016/S1473-3099(12)70222-0. Epub 2012 Sep 18.
Low birthweight is a significant risk factor for neonatal and infant death. A prominent cause of low birthweight is infection with Plasmodium falciparum during pregnancy. Antimalarial intermittent preventive therapy in pregnancy (IPTp) and insecticide-treated mosquito nets (ITNs) significantly reduce the risk of low birthweight in regions of stable malaria transmission. We aimed to assess the effectiveness of malaria prevention in pregnancy (IPTp or ITNs) at preventing low birthweight and neonatal mortality under routine programme conditions in malaria endemic countries of Africa.
We used a retrospective birth cohort from national cross-sectional datasets in 25 African countries from 2000-10. We used all available datasets from multiple indicator cluster surveys, demographic and health surveys, malaria indicator surveys, and AIDS indicator surveys that were publically available as of 2011. We tried to limit confounding bias through exact matching on potential confounding factors associated with both exposure to malaria prevention (ITNs or IPTp with sulfadoxine-pyrimethamine) in pregnancy and birth outcomes, including local malaria transmission, neonatal tetanus vaccination, maternal age and education, and household wealth. We used a logistic regression model to test for associations between malaria prevention in pregnancy and low birthweight, and a Poisson model for the outcome of neonatal mortality. Both models incorporated the matched strata as a random effect, while accounting for additional potential confounding factors with fixed effect covariates.
We analysed 32 national cross-sectional datasets. Exposure of women in their first or second pregnancy to full malaria prevention with IPTp or ITNs was significantly associated with decreased risk of neonatal mortality (protective efficacy [PE] 18%, 95% CI 4-30; incidence rate ratio [IRR] 0·820, 95% CI 0·698-0·962), compared with newborn babies of mothers with no protection, after exact matching and controlling for potential confounding factors. Compared with women with no protection, exposure of pregnant women during their first two pregnancies to full malaria prevention in pregnancy through IPTp or ITNs was significantly associated with reduced odds of low birthweight (PE 21%, 14-27; IRR 0·792, 0·732-0·857), as measured by a combination of weight and birth size perceived by the mother, after exact matching and controlling for potential confounding factors.
Malaria prevention in pregnancy is associated with substantial reductions in neonatal mortality and low birthweight under routine malaria control programme conditions. Malaria control programmes should strive to achieve full protection in pregnant women by both IPTp and ITNs to maximise their benefits. Despite an attempt to mitigate bias and potential confounding by matching women on factors thought to be associated with access to malaria prevention in pregnancy and birth outcomes, some level of confounding bias possibly remains.
低出生体重是新生儿和婴儿死亡的一个重要危险因素。导致低出生体重的一个主要原因是孕妇在怀孕期间感染疟原虫恶性疟。在疟疾稳定传播地区，孕妇接受抗疟药间歇性预防治疗（IPTp）和经杀虫剂处理的蚊帐（ITN）可显著降低低出生体重的风险。我们旨在评估在疟疾流行国家常规规划条件下，孕妇疟疾预防（IPTp 或 ITN）在预防低出生体重和新生儿死亡方面的有效性。
我们使用了来自 2000-10 年非洲 25 个国家的全国性横断面数据集的回顾性出生队列。我们使用了来自多个指标群集调查、人口与健康调查、疟疾指标调查和艾滋病指标调查的所有可用数据集，这些数据截至 2011 年都是公开的。我们试图通过对与妊娠期间疟疾预防（ITN 或 IPTp 联合磺胺多辛-乙胺嘧啶）和分娩结局相关的潜在混杂因素进行精确匹配，来限制混杂偏倚，这些因素包括当地疟疾传播、新生儿破伤风疫苗接种、产妇年龄和教育程度以及家庭财富。我们使用逻辑回归模型来检验孕妇疟疾预防与低出生体重之间的关联，以及使用泊松模型来检验新生儿死亡率的结局。这两个模型都将匹配层作为随机效应，同时通过固定效应协变量来考虑其他潜在的混杂因素。
我们分析了 32 个国家的横断面数据集。在首次或第二次妊娠期间接受完全疟疾预防的孕妇（接受 IPTp 或 ITN）与新生儿死亡风险降低相关（保护效力[PE]为 18%，95%CI 4-30；发病率比[IRR]为 0.820，95%CI 0.698-0.962），与未受保护的母亲所生的新生儿相比，在进行精确匹配并控制潜在混杂因素后。与未受保护的孕妇相比，在首次和第二次妊娠期间接受完全疟疾预防的孕妇，通过 IPTp 或 ITN 接受孕妇疟疾预防，与降低低出生体重的几率相关（PE 为 21%，14-27；IRR 为 0.792，0.732-0.857），这是通过母亲感知的体重和出生大小的组合来衡量的，在进行精确匹配并控制潜在混杂因素后。
孕妇疟疾预防与常规疟疾控制规划条件下的新生儿死亡率和低出生体重的显著降低相关。疟疾控制规划应努力通过 IPTp 和 ITN 为孕妇提供全面保护，以最大限度地发挥其效益。尽管我们试图通过匹配认为与孕妇获得疟疾预防和分娩结局相关的因素来减轻偏差和潜在混杂的影响，但可能仍存在一定程度的混杂偏倚。
