Scientists investigated the relationship between maternal age and non-genetic birth anomalies, and their results were recently published in the journal BJOG: an International Journal of Obstetrics & Gynaecology.
The researchers analysed 31,128 pregnancies complicated by non-chromosomal developmental disorders, using data from the Hungarian Case-Control Surveillance of Congenital Abnormalities between 1980 and 2009. They compared the data with 2,808,345 births registered with the Central Statistical Office in Hungary in the same 30 years.
“First, we tried to determine the ten-year age period during which the fewest such congenital abnormalities occurred. We found that between 23 and 32 can be the ideal age for giving birth. Then we identified the age groups where the risk is higher compared to this safest period,” says Dr. Boglárka Pethő, assistant professor at Semmelweis University and the first author of the study.
Previous research has confirmed the correlation between genetic disorders (e.g., Down syndrome) and maternal age. However, the literature is still incomplete in the case of non-chromosomal anomalies.
“Non-genetic birth disorders can often develop from the mothers’ long-term exposure to environmental effects. Since the childbearing age in the developed world has been pushed back to an extreme extent, it is more important than ever to react appropriately to this trend. Our research can play an important role in establishing modern and safe pregnancy care and screening protocols,” explains Prof. Nándor Ács, director of the Department of Obstetrics and Gynecology at Semmelweis University.
The researchers found that the risk of developing non-chromosomal abnormalities increased by 20% in general for births under the age of 22 and by 15% above the age of 32 compared to the ideal childbearing age (23-32).
Of anomalies affecting only young mothers, central nervous system malformations of the fetus were the most prominent – the risk of their development can generally increase by 25% in the category under the age of 22. The rise is even higher in the age below 20.
Among the abnormalities affecting only the fetuses of older mothers, the risk of congenital disorders of the head, neck, ears and eyes showed a doubled increase (by 100%), which was significantly more noticeable in pregnancies over the age of 40. A large increase (34%) in congenital malformations of the urinary system were also detected in the fetuses of advanced maternal age.
According to data from the Hungarian Case-Control Surveillance of Congenital Abnormalities, between 1980 and 2009, 65% of babies born with non-genetic abnormalities were boys. One of the reasons could be that minor developmental disorders of the penis are prevalent.
Among the possible abnormalities affecting both age groups, the risk of heart defects was 7% higher in the fetuses of young mothers (below 22) and 33% in the case of more mature mothers (above 32).
The risk of developing cleft lip and palate can increase by 9% in children of young mothers and by 45% in pregnancies over the age of 32.
The risk of fetal genital malformations can be 15% higher for young mothers and 16% higher for older mothers.
The risk of musculoskeletal anomalies increased by 17% for babies of very young mothers and 29% for older mothers.
The risk of congenital disorders in the digestive system increased by 23% and 15% for young and mature mothers, respectively.
“We can only assume why non-chromosomal birth anomalies are more likely to develop in certain age groups.
For young mothers, it could be mainly lifestyle factors (e.g., smoking, drug or alcohol consumption) and that they are often not prepared for pregnancy. Among advanced-aged mothers, the accumulation of environmental effects such as exposure to chemicals and air pollution, the deterioration of DNA repair mechanisms, and the aging of the eggs and endometrium can also play a role.
However, further research is needed to identify the exact causes,” adds Dr. Boglárka Pethő.
3-5% of births worldwide are estimated to end with some form of developmental disorder and have been among newborns’ leading causes of death.
“Reducing the incidence of developmental disorders should be a priority for the society as a whole. They place a huge emotional burden on families and an extraordinary weight on health and social care systems. In the United States, for example, 3% of hospital cases resulted from these anomalies in 2013, and 22.9 billion dollars were spent on their treatment alone,” explains Prof. Nándor Ács.
The experts warn that prevention is crucial in the case of mothers aged 32 or more. They recommend taking folic acid and vitamins and adapting screening protocols to age-related risk factors worldwide.
Photo: Balint Barta, Attila Kovacs – Semmelweis University; Cover photo: iStock – Natalia Kuzina