Notes

For first research steps:
Research by Bristol University that was published 2016
http://jamanetwork.com/journals/jamapediatrics/article-abstract/2543281 http://edition.cnn.com/2016/08/15/health/acetaminophen-pregnancy-kids-adhd/
There are older studies by Norwegian researchers from 2014 that claim the same. But to find out about the amount of paracetamol one has to take, I found warnings that vary from more than ten times to not more than 28 days of the pregnancy (I assume one tablet a day). There are many questions for which one would have to read the actual still ongoing study by the Bristol University. Also, I would not recommend to take painkilers at all unless absolutely necessary. Unfortunately the few researches about the postnatal impacts of the various existing painkillers during pregnancy are mostly funded by the pharma industry. Also, the brain development stops when the baby is about 15 months old. So, there should be multifactorial reasons taken into account.
Also interesting to mention is: "the researchers discovered that a mother using acetaminophen at 18 weeks of pregnancy was associated with a greater chance of her child becoming hyperactive or developing conduct problems. At 32 weeks into pregnancy, a mother's use of acetaminophen was linked to higher odds of her child having emotional symptoms, conduct problems and hyperactivity symptoms."