Schlotz W, Jones A, Phillips DI, Gale CR, Robinson SM, Godfrey KM. Lower maternal folate status in early pregnancy is associated with childhood hyperactivity and peer problems in offspring. J Child Psychol Psychiatry. 2010;51(5):594-602.
Prospective cohort study
The authors tested 100 mothers for red cell folate levels at the end of the first trimester, and folate intake was assessed throughout participants’ pregnancies. Head circumference of the newborns was measured and weight was measured at birth and 9 months of age. When the children were 8.7 years of age, the mothers were asked to complete a questionnaire on the behavior of their children covering hyperactivity, emotional symptoms, conduct problems, and peer problems. The authors controlled for maternal smoking, alcohol consumption, and gender.
Red cell folate levels and total folate intake levels were both found to be lower in the mothers of those children later reported to have high levels of hyperactivity and peer problems. The range of folate intake for mothers was 328.5–624.4 mcg in early pregnancy and 269.9–410 mcg in late pregnancy. Controlling for mothers’ smoking and drinking alcohol during pregnancy did not change the results.
This study is the first to show an association between folate status of the mothers and behavioral outcomes in their children. In addition, they also found that decreased head-growth velocity was also associated with lower folate levels during pregnancy. It should be noted that head growth is a rough indicator of brain growth.
However, there was an association here, indicating that in utero folate status does affect neurodevelopment, and decreased fetal brain growth is one of the results.
However, there was an association here, indicating that in utero folate status does affect neurodevelopment, and decreased fetal brain growth is one of the results. It is well known that inadequate prenatal folate intake will affect other aspects of nervous system development, evidenced by its relationship to spina bifida and other spinal dysraphisms. This study also provides information as to when folate status may be more important. In this case, the evidence points to the first trimester. In fact, other studies have shown that nutritional status in early pregnancy is more influential than it is later in pregnancy.1
It is concerning that nutrition could play such a significant role in the growing fetus at a time that many mothers may not even know they are pregnant or may believe prenatal nutrition is not particularly important. What is even more concerning is that the range of folate intake for the mothers in this study did not fall far out of the recommended minimum prenatal dose of 400 mcg. It is possible that other confounding factors will affect the folate status and usable folate that is consumed, such as tobacco smoke, oral contraceptives, trimethoprim, methotrexate, or sulfasalazine. Therefore, maternal use before pregnancy may create a further disadvantage when compared to other women not using these substances.
Folate deficiency is known to decrease fetal cellular replication,2 especially in the brain,3,4 leading to smaller brain size5 and behavioral problems.6 It is possible that prenatal folate deficiency affects the risk of later hyperactivity through its influence on dopaminergic system development,7 but this has yet to be studied. Other research makes a fairly solid connection between folate and attention deficit hyperactivity disorder (ADHD). Pediatric leukemia survivors who have mutations in 5,10-methylenetetrahydroreductase (MTHFR), a crucial enzyme that provides usable folate for DNA synthesis, show ADHD symptoms later in life.8 This could be further affected by chemotherapeutic folate antagonists (in particular methotrexate) commonly used in these patients.
The authors themselves state that there are many confounding factors here, especially after the child is born. However, when one looks at the past literature, it makes sense that behavior would be affected. It might not be the only factor, but it certainly is an important one to consider when counseling mothers for their family planning. This might be even more important in those mothers who suffer themselves from attention deficit disorder (ADD), ADHD, or depression. In addition, it is important to note that mothers who have a past history of delivering a child with a neural tube defect have a significantly increased risk of neural tube defects in subsequent births. Therefore, those mothers need much higher levels of folate intake, up to 4 mg, starting one month before they become pregnant.