Map of Simcoe Muskoka

Pregnancy and Before

Congenital Anomaly Rate

Neural Tube Defects
Down Syndrome
Cleft Palate and/or Cleft Lip
Congenital Heart Defects
Musculoskeletal Anomalies

The term congenital anomaly refers to any physiological or structural abnormality that is present at the time of birth. More than 3,000 congenital anomalies have been identified, such as neural tube defects, heart and circulatory system defects, musculoskeletal anomalies, cleft palate or lip, and Down Syndrome. These data come from the Canadian Congenital Anomalies Surveillance System.

Changes in congenital anomaly rates over time can be a consequence of changes in the underlying rate of congenital anomalies in the population, changes in the way that anomalies are coded, or changes in diagnostic techniques. Improved capacity for prenatal screening and diagnosis of congenital anomalies may lead to an increase in pregnancy termination, which would lead to a decrease in the rate of congenital anomalies reported per 10,000 births.

Overall Congenital Anomalies Rate

The overall congenital anomalies (CA) rates for Simcoe Muskoka and Ontario have remained relatively stable. In 2015, the CA rate was 563/10,000 births (550.7, 575.3) in Ontario and 602/10,000 births (537.0, 671.74) in Simcoe Muskoka.


Neural Tube Defect Rate

Neural tube defects (NTD) are birth defects of the brain and spinal cord. Folic acid supplementation prior to and during early pregnancy can reduce the risk of NTDs. In 1998, fortification of a variety of cereal grain products (e.g. flour and cornmeal) with folic acid became mandatory in Canada, which has resulted in further reductions in the rate of neural tube defects across the country.

The rate of neural tube defects in Ontario has decreased significantly from 1978 (20 per 10,000 births (17.4, 22.4)) to 2015 (4 per 10,000 births (2.8, 4.9)). In Simcoe Muskoka, on average fewer than 5 babies are born with an NTD each year.


Down Syndrome

Down syndrome is a genetic disorder which occurs as a result of trisomy 21, where an embryo has three copies of the 21st chromosome, instead of only two. The likelihood of producing an embryo with Down syndrome increases with maternal age, but no other risk factors have been identified. Down syndrome leads to delays in physical growth and neurodevelopmental disability, and individuals affected by Down syndrome possess characteristic facial features.

Down syndrome is not a common congenital anomaly identified in Simcoe Muskoka, and the rates in Simcoe Muskoka and Ontario have not changed from 1978 to 2015. The annual rate across this time period in Simcoe Muskoka was 10 per 10,000 births (8.6, 11.7) and for all of Ontario the rate was 13 per 10,000 births (12.9, 13.5).


Cleft Palate and/or Cleft Lip

Orofacial clefts (cleft palate and/or cleft lip) comprise two distinct anomalies: cleft palate, and cleft lip (which can occur with or without cleft palate). Abnormal facial development in infants affected by orofacial clefts can be seen as a split or opening in the lip or palate. Orofacial clefts often occur in association with other major anomalies, but no consistent risk factors have been identified.

Orofacial cleft diagnoses are not particularly prevalent, with fewer than 10 cases diagnosed per year, on average, in Simcoe Muskoka. The average annual rate from 1978 to 2015 for Simcoe Muskoka was 18 per 10,000 births (15.8, 19.8), similar to the rate for all of Ontario at 15 per 10,000 births (15.0, 15.6).

Congenital Heart Defects

Congenital heart defects (CHD) are problems or flaws in the structure of babies’ hearts at birth. They are among the most common congenital anomalies, and are a leading contributor to infant death from congenital anomalies. There is evidence that folic acid supplementation may reduce the risk of CHD.

The rate of CHD in Simcoe Muskoka is similar to the rate observed for all of Ontario, with 99 cases per 10,000 births (73.5, 131.0) in Simcoe Muskoka in 2015, and 100 per 10,000 births in Ontario (95.2, 105.9). The rate has increased slightly over time, from 49 per 10,000 births (29.0, 77.2) in Simcoe Muskoka in 1978 to 99 per 10,000 births in 2015, but no consistent trend is evident.


Musculoskeletal Anomalies

Musculoskeletal anomalies are malformations or deformities of muscle and/or bone tissue in the limbs or the trunk or head (axial) that are present at birth. Musculoskeletal anomalies include a broad range of anomalies including reductions, deformities and dislocation of limbs, scoliosis, spina bifida and macrocephaly. Causes of musculoskeletal deformities are varied including nutritional deficiency, physical damage to the fetus, physical damage occurring during birth and teratogenic agents, but many causes are poorly understood.

The average annual rate of musculoskeletal anomalies across 1978 to 2015 in Simcoe Muskoka was 121 per 10,000 births (115.8, 126.1), significantly lower than the rate across all of Ontario of 131 per 10,000 births (129.7, 131.7). The annual rates in Simcoe Muskoka have remained relatively stable, while they have declined slightly across Ontario for the period 1978 – 2015. In 2015, the rates of musculoskeletal anomaly had equalized at 103 per 10,000 births (76.9, 135.9) in Simcoe Muskoka; and 103 per 10,000 births (97.8, 108.8) for all of Ontario.


For more information on folic acid use during pregnancy in Simcoe Muskoka, please see the HealthSTATS page on folic acid supplementation. For more information on pregnancy and health, please visit the health unit’s website on health before pregnancy.