In the present study, a prevalence of 5.58 per thousand births (0.56% or 55.8 per 10,000 births) was reported. This prevalence is consistent withother African countries, however, it probably does not reflect the reality of the national situation. In fact, the census of CM is not systematically carried out throughout the country and health programs have not integrated routine prenatal screening for CM and do not consider this problem as a priority at this time. In addition, several malformations may only be revealed after the neonatal period and, therefore, will not be included in our census. Inadequate description of some cases of CM induces global under-reporting of malformations.
In Congo, a retrospective analytical study in the city of Lubumbashi carried out between 2010 and 2011 across 11 maternity clinics showed a prevalence of 58.4 per 10,000 births (0.58%) . A similar prevalence (0.57%) was also found in a multicenter prospective study conducted at Clinical Universities of Kinshasa .
In Egypt, a study conducted between 1995 and 2009 showed a frequency of CM of 2% .
In Nepal, the prevalence of congenital defects was 52.0 per 10,000 .
In France, the prevalence of CM at birth is estimated in 3-4%  of live births and this concerns only stillbirths and alive children, whereas early spontaneous abortions are excluded; This makes studying the frequency of congenital anomalies among all pregnancies difficult because most often the etiological diagnosis is not established in case of early abortion.
In Canada, CM affect approximately 3-5% of newborns . At the same time, in the United States, according to data from the Centers for Disease Control and Prevention (CDC), CM affect one in 33 births, or 3.0% of all live births .
The most frequently reported malformations in our series were:
- Osteoarticular and muscle abnormalities with a rate of 33% (equivalent to 35 per 10,000 total births), of which 17.4% of clubfoot, 7.7% of omphalocele, 7.1% of supernumerary fingers, followed by short limbs with a rate of 6.4%, and laparoschisis 5.1%. In Egypt, the rate of musculoskeletal abnormalities is 8.82% (1.8 / 1000) . In Canada, the prevalence of limb malformations is 3.5 per 10,000 total births, and the prevalence of laparoschisis is 4.4 per 10,000 total births in 2009 , whereas in our study this rate is 1, 8 for 10,000 births.
- CM of the nervous system with a percentage of 18% of which 31% of hydrocephalus (5.9 per 10,000 total births), 26.2% of anencephaly (versus 5 per 10,000 total births), 20, 24% spina bifida (3.8 per 10,000 total births). Nevertheless, these anomalies are the most frequent malformations in Egypt with a rate of 26.92% (5.5 / 1000) according to a study conducted between 1995 and 2009 .
In our context, the prevalence of neural tube defects is 16.5 per 10,000 total births, whereas in the European Union, the prevalence of neural tube defects (NTDs) decreased by 10.5 per 10,000 total births in 2004 to 9.4 in 2008 . In England and Wales, the prevalence of NTDs remained stable, ranging from 14 to 18 cases per 10,000 total births during the period 1995-2004. In Sweden, the prevalence of spina bifida also decreased from 5.5 per 10,000 during the 1988-1992 period to 2.9 per 10,000 during the period 1999-2003, mainly due to prenatal diagnosis and termination of pregnancy. . In Nepal, the prevalence of selected NTDs was 4.0 per 10,000 .
In the United States, the prevalence of spina bifida increased from 4.2 to 2.9 per 10,000 total births during a mandatory folic acid fortification period (1998-2002) .
In Canada, the prevalence of neural tube defects has decreased significantly from 7.6 to 4.1 per 10,000 total births between 1996-2007 , including spina bifida (5.5 → 2.7), anencephaly and similar abnormalities (1.1 → 0.8), encephalocele (1.1 → 0.6) and this regression is due to folic acid supplementation and prenatal diagnosis.
- Malformations of the eye, ear, face and neck represent 12% (12.7 per 10,000 total births), of which cranio-facial dysmorphia represent 51.78% (or 6.6 10,000 total births).
- Genetic abnormalities represent 8.5% (9 per 10,000 total births), 87.5% of which are Down syndrome (8 per 10,000 total births). In Egypt, these anomalies account for 25% (5.1 / 1000).
A study conducted in the Rhône-Alpes region over a period of 1981-2009 showed that the most frequently reported malformation is Down syndrome with a prevalence of 28.7 per 10,000 in 2009, and after early detection by bias of antenatal diagnosis the rate of medical termination of pregnancy (MTP) reached 84% in 2009 with one MTP out of two.
In Canada, Down syndrome has an almost stable prevalence of 14.1 per 10,000 total births between 1998-2007 .
- CM of the circulatory system represent in our series a rate of 8,08% (8,6 per 10,000 total births), against 6,55% (0,13 / 1000) in Egypt .
The prevalence of congenital heart disease in Canada is 85.1 per 10,000 total births (2009), 45% of which relate to Down syndrome, while in France, the prevalence of congenital heart disease was 83.8 between 2000-2005 .
- Genitourinary anomalies are estimated at 7.44% (8 per 10,000 total births), with 28% of hypospadias, 28% of micropenis, and 24% of ambiguous genitalia. In Egypt, the rate is 18.51% (3.8 / 1000).
- The cleft lip and cleft palate present a rate of 4.47% (4.8 per 10,000 total births). This rate reaches 12% in France. In Canada, the prevalence of cleft lip and palate during the period of 1998-2007 was 16.3 per 10,000 total births .
CM are a source of high mortality. According to the WHO; the number of newborns who die before the age of 28 days due to congenital anomalies is estimated at 276,000 each year . The most common serious congenital anomalies are CM of the heart and neural tube as well as Down syndrome or Trisomy 21.
In our series, the perinatal mortality rate caused by CM is 30.6%. In developed countries, 20 to 25% of total perinatal mortality is due to CM, and represent the leading cause of death in France.
In Canada, congenital anomalies affect 8 to 10% of stillbirths. They accounted for 23.2% of all deaths of children under the age of 12 months between 2003-2007, including 23.3% of neonatal deaths, and contributed to an overall infant mortality rate of 5.0 per 1,000 a live births in 2006-2007 , .
In the United States, congenital anomalies are a major cause of infant mortality, accounting for 20.8% of all infant deaths in 2016 .
One-sixth of malformed children are polymalformed. Polymalforms account for 4.5% of stillborn children and less than 0.5% of live children . In our study, 26.5% of malformed persons are polymalforms.
Among the 75 newborns who died, there were 33 cases of polymalformative syndromes, which represents 44%, 8 cases of anencephaly (10.6%), 3 cases of esophageal atresia (4%), and 2 cases of thanatophoric dysplasia (2.6%), 2 cases of laparoschisis (2.6%) and various isolated cases representing 1.3%: Dandy walker syndrome, hydrothorax, hydrocephalus, diaphragmatic hernia...
In our study, antenatal diagnosis was performed in 28.6% of cases, of which 5.7% (4 cases) in the first trimester, 47% (33 cases) in the 2nd trimester, and 48.5% (34 cases) in the third trimester. Whereas in more than two thirds of cases (71.4%) the diagnosis was made at birth during a systematic clinical examination of newborns.
In a Parisian study,  carried out between 1981 and 2000, prenatal diagnosis has made significant progress in the early detection of congenital malformations, from 16.2% (95% CI 13.8-18.6) in 1983 to 69.1% (95% CI 66.7-71.5) of the cases in 2000.
In addition, the present study has identified seven groups of malformation associations: (Table 3)
- The first association gathered trisomy 8, pelvic kidney, microphthalmia, sacral agenesis, epidermal sinus, agenesis of the nose cartilage, and clubfoot. We note that in Trisomy 8, there was a facial dysmorphism that can combine agenesis of the nose cartilage, ophthalmological anomalies with sunken eyes and microphthalmia, urinary abnormalities, bone malformations like sacred agenesis with epidermal sinus and clubfoot.
Also in sacred agenesis or caudal regression syndrome; there is agenesis of the sacro-coccygeal spine, deformation of the pelvis, club feet, renal agenesis or renal ectopia..
- The second group includes craniosynostosis, pectus excavatum, limb asymmetry, scoliosis, cleft palate, and ureteric dilatation; scoliosis is a malformation that can be associated with craniosynostosis, heart, kidney and bone abnormalities in the limbs. Cleft palate is often present in Apert syndrome which is a syndromic form of craniosynostosis.
- The third association includes an invisible bladder, absence of thalami, pectus carinatum, hyperflexion limbs, cardiomegaly, amniotic bridle and polycystic kidney disease. In the case of an invisible bladder (vesical extrophy), we have noted cardio-vascular malformations, renal abnormalities, abnormalities of the limbs and malformations of the central nervous system. These central nervous system malformations, limb and renal malformations are also found in amniotic bridle disease.
- The fourth association comprised: narrow thorax, craniofacial dysmorphia, microdactyly, and short limbs; these abnormalities can be part of polydactyly syndrome - short ribs - micromelic dwarfism (short limbs, microdactyly), narrow thorax, microcephaly, cardiac, urinary or digestive abnormalities ...
It can also be part of a dysplasia including a thanatophore dwarfism with prominent forehead macrocephaly that is part of a cranio-facial dysmorphism, narrow chest and short limbs.
- The fifth association includes gingival hypertrophy, macroglossia, exophthalmia, ichthyosis, limb malformation and Dandy Walker syndrome. In congenital ichthyosis, there is ophthalmic impairment, gingival hypertrophy, macroglossia. Some forms of ichthyosis such as Sjögren-Larsson's Syndrome is characterized by neurological involvement.
There are some forms associated with bone involvement such as chondrodysplasia punctata.
- The sixth association includes acardiac fetus, glossoptosis, Pierre Robin syndrome, retrognatism. Pierre Robin's syndrome is characterized by craniofacial anomalies, micro / retrognatism, glossoptosis and respiratory obstruction. It can be isolated or included as part of a polymalformative syndrome. The acardiac fetus acephalic is characterized by primary cardiac dysmorphogenesis with placental vascular anastomoses.
- The seventh association associates canines, deformed thorax, hypertelorism, retrognathism, low-set ears. The natal teeth are part of the clinical picture of more than 50 malformative syndromes of which the most frequent are: Hallerman-Streiff syndrome or ocular-mandibular dyscephaly, Wiedemann-Rautenstrauch syndrome, Elli-van Creveld syndrome, chondroectodermal dysplasia (Ellis Van Creveld syndrome), cranio-facial dysostosis, congenital pachyonychia: rare genodermatosis affecting the ectodermal tissues which is characterized mainly by a thickening of all the nails, labio-palatal clefts, Trisomy 13.
The combination VACTERL / VATER defined by the presence of a set of vertebral malformations, renal and limb abnormalities, is found in the first three associations described in Table 3.