Babies are deemed small for gestational age (SGA) if their birth weight is in the lowest 10% of babies born.
SGA is primarily caused by fetal growth problems during pregnancy, such as intrauterine growth restriction (IUGR). This can develop when the fetus fails to receive the required nutrients and oxygen it needs to grow.
At birth, SGA can cause an array of complications, such as reduced oxygen levels, polycythemia (excess red blood cells) and low blood sugar. It can also increase the risk of health problems later in life, such as diabetes, high blood pressure, obesity, cardiovascular disease and mental health issues.
Folic acid - a type of B vitamin - is already highly recommended for women of a childbearing age due to studies claiming the vitamin can reduce the risk of a child developing neural tube defects, such as spina bifida. The American Pregnancy Association say prior to and during pregnancy, women should take around 400 mg of folic acid a day.
The researchers from this latest study - including Khaled Ismail of the University of Birmingham in the UK - set out to determine how folic acid supplementation before conception and during pregnancy affected offspring's risk of SGA.
Risk of SGA lowest among women who start taking folic acid before conception
By analyzing data from a UK regional database, the team identified 108,525 pregnancies whereby data on mothers' folic acid supplementation was accessible.
Almost 85% of women had taken folic acid during pregnancy. Information on when women began taking folic acid was available for 39,416 women. Of these, 10,036 (25.5%) began taking folic acid prior to conception.
Overall, 19.3% of babies were born SGA; 13.4% of these babies had a birth weight in the lowest 10%, while 7% of babies had a birth weight in the lowest 5%.
Results of the study revealed that the highest rates of SGA occurred among babies whose mothers had not taken folic acid before conception or during pregnancy, with 16.3% of these babies born with a weight in the lowest 10% and 8.9% born with a weight in the lowest 5%.
Of the mothers who began taking folic acid during pregnancy, 13.4% had babies with a birth weight in the lowest 10%, while 7.1% had babies with a birth weight in the lowest 5%.
Among women who began taking folic acid prior to conception, however, the percentage of babies with a birth weight in the lowest 10% stood at 9.9%, while the percentage with a birth weight in the lowest 5% was 4.8%. This indicates that taking folic acid before conception can significantly reduce the risk of SGA.
Commenting on their findings, Ismail says:
"Increased uptake of folic acid prior to pregnancy and throughout the first trimester could have significant public health benefits given the poor outcomes associated with SGA babies. New strategies are therefore vital to improve the lives of both mothers and babies."
John Thorpe, deputy editor-in-chief of BJOG: An International Journal of Obstetrics & Gynaecology, adds that the team's findings are of "particular importance," as there are currently no established treatment options for SGA.
Medical News Today recently reported on a study suggesting that low to moderate amounts of alcohol during pregnancy may not increase the risk of adverse birth outcomes, including low birth weight and preterm delivery.
Written by Honor Whiteman