The main findings of this study are a notably statistically significant association of alcohol drinking, maternal chronic illness, khat chewing, and chemical exposure during pregnancy to the congenital anomalies. Besides, folic acid supplementation during the early period of pregnancy had a protective effect on the induction of congenital anomalies.
Our study showed that alcohol drinking of any amount during pregnancy increases the risk of occurrence of congenital anomalies by about three times as compared to its counterparts. This is in line with the previous studies conducted in Ethiopia (12, 15) and California (17). On the other hand, a very recent case-control study conducted in Bale Zone, Southeast, Ethiopia indicated that drinking alcohol had hardly any significant association with the occurrence of congenital anomalies (18). This might be due to the differences in drinking alcohol cultures. As alcohol is capable of transmitting through placental membranes, it causes direct effects to the organogenesis of the developing embryo and fetuses and leading to structural abnormalities (19–22).
Infants born from mothers who had a maternal illness during pregnancy were six times more likely to develop congenital anomalies compared to infants born to mothers who were free from maternal illnesses. Our finding is strongly supported by the study that dealt with the prevalence and associated factors of birth defects in Northwest Ethiopia (12). Similarly, maternal illnesses, like febrile illness and chronic diseases like diabetes mellitus were reported as they were associated with the occurrence of congenital anomalies (23, 24). Unlike current observation, however, other study done in Ethiopia revealed that maternal illness had a hardly significant association with the existence of an infant with congenital anomalies (15). This difference might be due to a lack of knowledge on the definite time of the embryonic period at which maternal illness happened.
In this study, the mother who has been exposed to chemicals during the current pregnancy was 4.8 times more prone to have infants with congenital anomalies compared to their corresponding counterparts. Our finding is strongly supported by previous studies carried out by different researchers elsewhere (15, 18, 25–27).
A study conducted among Yemeni pregnant women and a case-control study among Southeast Ethiopian pregnant women revealed that khat chewing during the early period of pregnancy was 2.02 and 3 times more likely to deliver an infant with congenital anomalies compared to those who did not chew khat, respectively (50,51). Similarly, in the present study, khat chewing during pregnancy augmented the development of congenital malformation by four folds as compared to those non-khat chewing mothers.
In our study area, khat chewing is the commonest and most popular social practice in which most of the individuals, including pregnant women, were engaged. In addition, khat chewing had high cultural, traditional, and social values. Therefore, we emphasize that this highly popular, but harmful social activity was one of the biggest confrontations to the public health experts in Ethiopia. However, it is the one that public health experts and communities as general must deal with.
In the present study, the lack of folic acid supplementation had a significant association with the occurrence of congenital anomalies. Women who did not take folic acid supplementation during pregnancy had about 3.25 times more chances to have infants with congenital anomalies compared to their counterparts. Our finding is in line with studies done elsewhere reported that folic acid supplementation had a protective effect against congenital anomalies (10, 12, 15, 18, 28). In spite of the valuable protective role of folic acid, in Ethiopia, the use and coverage for folic acid supplementation is very limited (29). However, the Ethiopian Federal Ministry of Health establishes a policy that makes pregnant women have folic acid supplementation. The gap between well-established policy and lack of folic acid supplementation might be due to poor awareness of pregnant women and health professionals towards the use of folic acid supplementation.
The most prevalent congenital anomalies were neural tube defects followed by orofacial cleft and musculoskeletal anomalies. This finding is consistent with the previous studies conducted in Ethiopia (10, 12, 15, 30, 31).
Limitation of the study
Even though it has its own strength, this study has various limitations that must be admitted. Although diversified study participants are included in the present study. Hospital-based unmatched case-control study makes the result of this study less generalizable to the community. Even if it is a factor study/not the prevalence estimate, the study did not include the terminated pregnancy/cases of CAs. Moreover, since the study is only considering congenital anomalies at birth, those anomalies which are not detected at birth but later in life were not considered. Furthermore, the study has relied on externally visible congenital anomalies which are identified by clinical examination. Hence, congenital anomalies that need sophisticated procedures to be identified were likely to be missed.