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 Table of Contents  
Year : 2019  |  Volume : 26  |  Issue : 4  |  Page : 239-243

Incidence, spectrum and outcome of congenital anomalies seen in a neonatal intensive care unit in Southern Nigeria

1 Department of Paediatrics, Mother and Child Hospital, Akure, Ondo State, Nigeria
2 Department of Child Health, University of Benin Teaching Hospital, Benin City, Nigeria

Date of Web Publication4-Oct-2019

Correspondence Address:
Dr. Moses Temidayo Abiodun
Department of Child Health, University of Benin Teaching Hospital, Benin City
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/npmj.npmj_77_19

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Background: Congenital anomalies (CAs) refer to defects that are present in a newborn but occurred during intrauterine life. They can be due to genetic, modifiable environmental or multifactorial causes. There was no prior report of their burden in our state. Aims: This study aims to describe the incidence, spectrum, predisposing factors and outcome of CAs in our setting. Methods: It was a total population study of all neonates with major birth defects admitted into the unit during the study period. Their clinical–demographic features, diagnoses and outcome were entered into an excel sheet. Clinical detection of birth defects was based on standard diagnostic criteria. The data were analysed using IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp. Patterns and outcome of birth defects were presented as proportions. Selected characteristics were tested for possible association with birth defect using Fisher's exact test. The level of significance was set at P < 0.05. Results: The incidence of major CAs was 4.3/1000 live births. Female neonates were more affected (59.0%). Participants' mean gestational age was 37.7 ± 3.3 weeks. Central nervous system anomalies were the most common (38.5%) birth defects. These were followed by musculoskeletal, body wall and digestive system anomalies: 28.2%, 23.1% and 10.3%, respectively. One-third (33.3%) of the infants had multiple anomalies. Nearly three quarters of them (74.0%) were referred, 18.0% died while 5.0% were discharged alive. Conclusion: A wide range of CAs occur in our setting with dire consequences. Provision of relevant specialised multidisciplinary care is desirable. Furthermore, pubic enlightenment on its modifiable possible causes can reduce the burden.

Keywords: Congenital anomalies, outcome, prevalence, spectrum

How to cite this article:
Oluwafemi RO, Abiodun MT. Incidence, spectrum and outcome of congenital anomalies seen in a neonatal intensive care unit in Southern Nigeria. Niger Postgrad Med J 2019;26:239-43

How to cite this URL:
Oluwafemi RO, Abiodun MT. Incidence, spectrum and outcome of congenital anomalies seen in a neonatal intensive care unit in Southern Nigeria. Niger Postgrad Med J [serial online] 2019 [cited 2022 Dec 5];26:239-43. Available from: https://www.npmj.org/text.asp?2019/26/4/239/268598

  Introduction Top

Congenital anomalies (CAs) refer to structural or functional defects that are present in a newborn and occurred during intrauterine life.[1],[2] They are described as major, if associated with medical, developmental or social significance; otherwise, they are minor.[1] Major anomalies occur in about 2.5%–4.0% of live births but minor defects are more common in the population.[1],[3] Comprehensive registries with sophisticated screening tools often report higher prevalence of CAs than reports based on clinical diagnoses. The European Surveillance of Congenital Anomalies (EUROCAT) covering 1.5 million annual births in 22 countries recorded a total prevalence of major CAs of 2.4%.[4] Ahuka et al.[5] in Democratic Republic of Congo reported prevalence of 0.41%. In Nigeria, reported prevalence ranges from 0.71% in Sokoto in Northern Nigeria to 2.2% in Anambra, Eastern Nigeria.[6],[7] CAs are often described based on the underlying causes. Malformations refer to anomalies that result from abnormal tissue formation process in the embryo (agenesis, hypoplasia and dysplasia); disruption is due to an intrinsic damage (such as an interrupted blood supply) to an otherwise well-formed tissue; and deformation refers to an anomaly that is due to the effect of an external pressure (e.g., adverse uterine environ) on a normally formed fetal part.[3] CAs may occur singly or in a combination. The latter is described as a syndrome, sequence or association.[3]

Although genetic and environmental factors contribute to the occurrence of CAs, no specific cause is identified in about two-third of cases, perhaps being polygenic or multifactorial.[3] A family history of birth defects increases the risk of recurrence of the same defects as well as other malformations.[4],[6] Cytogenetic abnormalities and environmental factors account for 20% and 10% of birth defects, respectively. A wide range of physical, chemical and biological environmental agents have been proven to be teratogenic in early pregnancy. These include drugs (e.g., thalidomide, anticonvulsants and folic acid antagonists), irradiation and maternal infections (toxoplasmosis, rubella, cytomegalovirus, herpes and syphilis) as well as diabetes mellitus.[3] Hence, it is pertinent to identify and prevent such embryopathic factors, especially among women in the reproductive age–group.[2]

Nonetheless, CAs are often attributed to suprahuman superstitious causes in different cultural views without adequate health awareness.[8] Considering that there are no prior studies on CAs in our locale, it is necessary to document their spectrum, possible predisposing factors and outcome in the setting. This will enable pubic enlightenment on some modifiable causative factors and reduce the burdensome care often associated with birth defects.[2],[9]

  Methods Top

Study setting and participants

This was a cross-sectional study, done at a level II Neonatal Intensive Care Unit of the Mother and Child Hospital Akure (MCHA). This ultra-modern public facility provides Integrated Maternal Newborn and Child Health services to the state capital and suburbs as well as allied communities in neighbouring states. It was the busiest health facility in Ondo State, South western Nigeria.[10] Ethical clearance was obtained from the Research and Ethics Committee of MCHA (MCHA/REC/2012/03/no 02). Verbal informed consent was obtained from the parents of the infants, having explained the purpose of the study and emphasised that participation was voluntary. It was a total population study of all neonates (inborn and outborn) with major birth defects admitted at the centre during the study period (January 2014 to April 2015).

Data collection

Relevant information on the participants comprising sections on sociodemographic characteristics, antenatal history, clinical features, diagnosis and outcome was obtained on an excel sheet. The detection of CAs was by clinical examinations by the researchers and attending paediatricians. Echocardiography was not included in this study. Infants with hydrocephalus and concurrent lumbosacral myelomeningocele were classified as  Arnold- Chiari malformation More Details More Detailss.[11] A newborn with skeletal deformity, joint stiffness and 360° rotation of the knees backward was classified as arthrogryposis multiplex congenita.[12] Other multiple defects were described as syndromes, sequences or associations based on relevant standard diagnostic criteria.[3] Participant's outcome was described as discharged, referred, died or discharged against medical advice. The short-term outcome of each referred case was obtained by follow-up phone calls by the lead researcher. Total number of deliveries during the study period was obtained from the hospital delivery register.

Data analysis

The data were analysed using IBM SPSS Statistics for Windows, Version 20.0, IBM Corp. Armonk, NY, USA. Demographic data and patterns of birth defects were presented as frequencies and proportions. The defects were categorised by systems/syndromes. The incidence of major birth defects was computed by dividing the number of cases by number of live births, expressed per 1,000 live births. Outcomes were presented on pie charts. Sociodemographic variables associated with body wall defects and nervous system anomalies were tested with Fisher's exact test for statistical significance. The level of significance of each test was set at P < 0.05.

  Results Top

Incidence of congenital anomalies and baseline characteristics

Thirty-nine neonates with major birth defects were recruited during the study period, 36 (92.3%) of them were inborn and 3 (7.7%) were outborn. Two (5.1%) of the neonates were products of multiple gestations. Based on the total number of deliveries (8,307) at the centre during the study period, the incidence of major birth defects was 0.43% (4.3/1000 live births). Twenty-three (59.0%) of the affected neonates were females. Participants' mean gestational age was 37.7 ± 3.3 weeks. Their mean anthropometric measures were as follows: weight 2.8 ± 0.9 kg, length 43.9 ± 8.7 cm and occipitofrontal circumference 35.8 ± 9.1 cm. Elective/emergency caesarean section was their most common mode of delivery (51.3%). Maternal antenatal use of herbs occurred in 41.0% and attempted abortion in 2.6%. Further details of participants' baseline characteristics are shown on [Table 1].
Table 1: Baseline characteristics of the infants with major congenital anomalies (n=39)

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Spectrum of congenital anomalies

Central nervous system (CNS) anomalies were the most common (41.0%) birth defects among the participants. These were followed by musculoskeletal, abdominal wall and digestive system anomalies: 28.2%, 23.1% and 10.3%, respectively. One-third (33.3%) of the infants had multiple anomalies as follows: limb deformation including congenital talipes equinovarus occur commonly (26.7%) among infants with CNS defects; one participant with hydrocephalus had hypospadias while another with Arnold-Chiari malformation had cryptorchidism; spina bifida occurred in association with choanal atresia and malformed pinnae in one neonate. Three neonates with multiple defects were unclassified: (1) microcephaly, eye deformities and anterior abdominal wall defect (post-abortion attempt); (2) low set ears, small pinnae, pinhole external meatus, antimongoloid slant and cleft palate; (3) small for gestational age, microcephaly and dysmorphic facie/hypertelorism. The proportions of specific anomalies among the participants are shown in [Table 2].
Table 2: Spectrum of congenital anomalies among the participants (n=39)

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Outcome of the participants

Twenty-nine of the participants (74.4%) were referred to tertiary centres for neurosurgical and paediatric surgery interventions. One in every six participants (18.0%) died while 5.1% were discharged alive in the neonatal period [Figure 1]. Furthermore, [Figure 2] shows the short-term follow-up reports on some of the referred cases: 59.0% died while 21.0% had successful repairs.
Figure 1: Overall outcome of the participants

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Figure 2: Follow-up reports on referred participants

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Characteristics associated with selected congenital anomalies

Isolated abdominal wall defects occur more commonly than other types of defects among infants of young mothers (<35 years old) compared to those with higher maternal ages, but this did not attain statistical significance (35.0% vs. 10.5%; P = 0.06). Paternal age was not associated with body wall defects. Maternal antenatal alcohol use (22.2%) and herbal concoction ingestion (44.4%) were common among participants with body wall defects but not statistically significant (P > 0.05). Further details of variables tested for possible association with abdominal wall defects are shown in [Table 3]. In addition, none of the above variables had a significant association with CNS anomalies (P > 0.05).
Table 3: Maternal characteristics associated with abdominal wall defects among infants with major congenital anomalies

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  Discussion Top

This study confirms that CAs occur commonly in the locale, comparable to earlier reports of prevalence of 0.71% by Singh et al.[6] in Sokoto, Northern Nigeria and 0.41% by Ahuka et al.[5] in Democratic Republic of Congo but lower than the incidence of 2.2% by Ekwunife et al.[7] in Anambra, Eastern Nigeria and 2.4% reported in the EUROCAT population-based registry.[4] The higher incidences reported by Ekwunife et al.[7] and the EUROCAT registry [4] are apparently due to the inclusion of sonographic screening in their surveys. This highlights that clinical screening alone may not detect some anomalies, underestimating their burden in the community.[4] Hence, specialised tests including cytogenetic studies should be done promptly in at-risk neonates, especially if prenatal screening was not achieved.[13]

A wide range of birth defects was found in this study with CNS anomalies and musculoskeletal defects being the most common, similar to the report by Singh et al.[6] in North-West Nigeria while Ekwunife et al.[7] reported CNS and digestive system defects as the most common in their survey in Anambra State, South-East Nigeria. Furthermore, in a 10-year retrospective review in North-eastern Nigeria, Ambe et al.[14] reported that anterior abdominal wall defects (24.8%) and CNS anomalies (24.2%) were the most common birth defects at the centre. CNS development starts in the 3rd week of embryonic life when women are barely aware of the pregnancy. This often precludes early observance of relevant precautions, such as folic acid supplementation and avoidance of embryopathic agents, predisposing to CNS malformation, especially in developing settings with low levels of health information.[15] The most common musculoskeletal defects in this study were due to deformations which may be caused by uterine factors or crowded fetal parts in multiple gestations,[3] as seen in a minority of our participants.

Although multiple CAs occur in some of our participants with syndromic presentations in a few of them, a majority of the anomalies occurred singly. Likewise, most of the CAs (81.9%) reported in the series by Singh et al. involved single organs.[6] Lumbosacral myelomeningocele and hydrocephalus coexisted in some of our patients similar to earlier report by Alatise et al. in Ile-Ife South-West Nigeria that hydrocephalus was present in about a half of their patients with spina bifida cystica.[16] Multiple malformations can be due to underlying genetic defects with multisystemic manifestations, but they can also occur as a sequence in which a primary anomaly leads to several secondary deformations,[3],[17] as seen in the Pierre Robbin sequence in this report. Likewise, spina bifida often presents with limb hypotonia and deformations [18] as seen in some of our participants.

The outcome of major CAs is poor in this current study with over a half of referred cases dying on follow-up, consistent with several earlier reports from our medically underserved region.[14],[19] While some major malformations are not compatible with life, others require sophisticated surgical reconstructions as well as expensive rehabilitative therapies for optimal survival.[20] Such multidisciplinary care is often unavailable and unaffordable to affected families, without financial supports. This highlights the need to promote health foundations focusing on prevention and management of birth defects in resource-limited settings to reduce associated mortality and disability-adjusted life years.[21]

Although congenital malformations are sometimes attributed to superstitious causes, unhealthy lifestyles abound among females of reproductive age group,[22] as seen in the frequent antenatal alcohol and herbal concoction ingestion of some mothers of our participants. Furthermore, attempted abortion of an unplanned pregnancy leading to an unclassified multiple malformations was found in this survey. Some herbal preparations have been shown to cause post-natal organ damage previously in this setting.[23] This highlights the need for relevant public enlightenment. Although Ekwunife et al.[7] reported that abdominal wall defects were more common among infants of young mothers, a significant association was not found in this study (P = 0.06).

Other sociodemographic features associated with birth defects in the literature include lack of periconceptional use of folic acid, maternal age of above 35 years and birth order above 4.[24] Nonetheless, mean maternal parity was 2.5 in this study and mean maternal age was low, suggesting that cytogenetic defects due to a high maternal age are less likely among the participants. An extensive collaborative population-based study using case–control design to identify specific risk factors of CAs in our subregion is hereby recommended.

  Conclusion Top

A wide range of CAs occur in our setting with dire consequences. Provision of relevant specialised multidisciplinary care is desirable. Furthermore, pubic enlightenment on its modifiable possible causes can reduce the burden.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3]

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