Abstract:
Background: Birth defects have a great impact in middle and low income countries. Ninety four per cent of birth defects in newborns worldwide and 95 percent of deaths due to birth defects worldwide occur in these countries, Tanzania being among them.
In Tanzania, it is estimated that the prevalence of birth defects is 60.5 per 1,000 live births. Factors affecting birth defects can be genetic and non genetic. There are well established preventive programs which are addressing non genetic factors influencing birth defects in developed countries, however in Tanzania limited prevention strategies of birth defects are in place due to limited information on factors predetermining the occurrence of birth defects.
Objective: To determine factors associated with major structural birth defects (NTD or orofacial clefts or limb defects) among newborns delivered at Muhimbili National Hospital and Municipal hospitals in Dar-Es-Salaam.
Materials and Methods: This was a case control study involving newborns born from October, 2011 through February, 2012 at participating hospitals. A case was defined as any newborn live or stillbirth of a Dar es salaam resident with major structural birth defects delivered at participating hospitals during the study period. A control was defined as any live newborn of a Dar es salaam resident without any birth defects born at participating hospital during the study period. Next three newborns who were delivered after the case and met the control definition were recruited as study controls. Mothers for both cases and controls were asked for informed consent.
Data was analysed using statistical software Epi Info version 3.5.1 and MS Excel. Chi square (χ2) was used to compare proportions and to assess statistical significance. Confidence level of 95% and p value of less than 0.05 were considered statistically significant. Binary and multiple logistic regressions were employed to quantify and adjust factors influencing occurrence of structural birth defects.
Results: A total of 400 newborns participated in the study, 100 cases and 300 controls. Maternal and paternal mean ages were 25.9±5.9 and 32.5±7.2 years respectively. Among cases, the major structural birth defects found included NTD 39(39%), Limbs defects 50(50%) and Orofacial cleft 11(11%). We found higher odds on maternal fever [AOR=2.00, 95% CI: 1.14-3.52], maternal hypertension [4.00, 95% CI: 1.67-9.54] during pregnancy, and low birth weight newborns [AOR=3.48, 95% CI: 1.77-6.85]. Antimalarials use during pregnancy had lower odds [AOR=0.48, 95% CI: 0.28-0.84].
Conclusion: Maternal fever and hypertension during pregnancy, and low birth weight newborns are risks factors for developing structural birth defects. While antimalarials use during pregnancy was a protective factors against structural birth defects.
Recommendations: Early screening of pregnant mothers for hypertension and other causes of low birth weight or prematurity is highly needed through strengthening of Primary Health Care where ANC visits are done. We also recommend promotion of utilization of existing reproductive and child health and advocacy strategies to address the identified factors.
