Cerebral palsy is the most common physical disability among children, with about two per 1000 live-born infants being diagnosed with the disorder. In most children with cerebral palsy, the disability is caused by damage to the immature brain during pregnancy or birth that results in problems with movement.
Denmark and Norway have low income inequality and free access to education and offer high-quality antenatal care to pregnant women free of charge. Nevertheless, in our study recently published in the International Journal of Epidemiology, we found that the risk of having a child with cerebral palsy in these two countries varies by the parents’ educational level, and this educational gradient has been surprisingly stable over time.
Continue reading “Lower risk of cerebral palsy in the child if the parents have higher education”
Anwar T Merchant and Bryn E Davis
The Obstetrics and Periodontal Therapy (OPT) Study was an NIH-funded randomised controlled trial designed to evaluate whether periodontal treatment in pregnant women had any effect on preterm birth; its findings were published in 2006. The investigators randomly assigned about 800 women who had been pregnant for less than 16 weeks, and had periodontal disease, to one of two groups. One group received periodontal treatment during pregnancy, whereas the other group received treatment after pregnancy.
Although the study found that treatment controlled periodontal infection and reduced the microorganism load, there was no difference in preterm birth rates between the two groups. The investigators concluded that treating periodontal disease during pregnancy did not affect the risk of preterm birth. However, they also found that there were more stillbirths in the group that received treatment after pregnancy, suggesting that periodontal treatment may improve survival of fetuses. The potential bias resulting from the intervention affecting both the outcome (in this case, preterm birth) and survival (in this case, stillbirth) was acknowledged as a limitation.
Continue reading “Does correcting for bias caused by unequal survival in the treatment arms of a randomised controlled trial matter?”