Etiology and clinical presentation of birth defects: population based studyBMJ 2017; 357 doi: https://doi.org/10.1136/bmj.j2249 (Published 30 May 2017) Cite this as: BMJ 2017;357:j2249
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Coffee and cola drinks are widely consumed by pregnant women in the USA.
The Authors of this study should not discard 80% of presenting birth defects as of "non known etiology", since harmful agents were present in those pregnant uteri.
Competing interests: No competing interests
Feldkamp et al. reported the results from a retrospective observational study of birth defects. The study has sampling bias because no participants were included in the study and the data from population based surveillance system was collected from two hospital based records. Data from abortions record could be included which would influence birth defect prevalence in many pregnancies. Birth defect etiology is unclear, although approximately 50% of all congenital anomalies are of unknown origin and cannot be linked to a specific cause like genetic, environmental or other risk factors. The authors reported a prevalence of birth defects of 2.03% and 1.8% among all births and live births respectively. Only 20.2% of birth defects had an assigned definite cause and the rest were of unknown etiology. Two other comparison studies reported a prevalence rate of 2.24% and 5.5% from Boston hospital and Texas Defects Monitoring programme respectively.
In addition, the frequency of pregnancy termination following prenatal diagnosis of a congenital anomaly is lower in many low and middle income countries (LMICs) than in high income countries (HICs). The fact is elective pregnancy termination following prenatal diagnosis may be less available in certain LMICs than in HICs. Incidence rate is also higher in LMICs than HICs. Many LMICs lack a surveillance programme of incidence and prevalence report. So it is difficult to calculate the prevalence rates; according to the study conducted in Kenya (Sitkin, Nicole A. et al.), current calculation range is from 4 to 12 cases per 1,000 births and are likely to be underestimates because of stigma and exclusion.
Children with non-immediately life-threatening anomalies are more likely to survive until treatment than children with immediately life-threatening conditions. Hospital-based data therefore inherently biases the perception of relative incidence and prevalence such that immediately life-threatening conditions may appear to have a lower incidence than non-immediately life-threatening anomalies.
In many LMICs, births occur at home, either with traditional birth attendants or no attendants; cultural beliefs, lack of psychological support from family members, ignorance or lack of awareness about possible cures for defects may prevent families from seeking treatment. If families do seek care, they must often travel great distances to reach medical facilities.
According to WHO fact sheet (2016), 94% of birth defects occur in low and middle income countries, and indirect determinants are poor access to health care and screening, high risk related to nutritional factors, traditional remedies and maternal exposure to factors like smoking, alcohol and infections. Some ethnic communities (Jews/Finns) have a comparatively high prevalence of rare birth defect -- for example, cystic fibrosis, Haemophilia C.
However, India is the second largest populous country with a large number infant born annually with birth defects 6 - 7% -- that is, around 1.7 million birth defects annually (according to National Health Portal (NHP) of India). Indian people are at mild risk for birth defects -- for example, universality marriage, high fertility rate, unplanned pregnancies, poor coverage of antenatal clinics and poor nutritional status. Birth defects are significantly contributors to still births and early infant mortality rate. There are wide variations for infant mortality rate in different parts of India.
Birth defect detection strategies should focus on the control of birth defects. There are some strategies which have been proven for the control of birth defects, such as iodization, double fortification of salt, folic acid supplementation. Policy makers should focus on prevention through training medical professional and staff for medical genetics and genetic counselling in early detection of birth defects.
Sitkin, Nicole A. et al. “Congenital Anomalies in Low- and Middle-Income Countries: The Unborn Child of Global Surgery.” World Journal of Surgery 39 (2015): 36–40. PMC. Web. 7 June 2017.
Competing interests: No competing interests