A new report out Monday finds a troubling link: when women take the common painkiller acetaminophen when they are pregnant, their kids may be more likely to have behavioral problems such as hyperactivity. 
 
 But doctors have immediately questioned the inevitable headlines, and say this study does not show the pills affect unborn babies. 
 
 And even if it did, the overall rates are low. Just 5 percent of the kids in the study had behavior problems. 
 
 File photo of a pregnant woman. Media for Medical / UIG via Getty Images 
 
 Acetaminophen, sold generically and under the brand name Tylenol, is a top choice for pregnant women to use to control pain and fevers — it’s considered a safe painkiller. 
 
 But a few studies have suggested that it might affect the brain development of unborn children. A study in 2013 found that women who took acetaminophen frequently during pregnancy raised the risk of behavior problems in their children by 70 percent. 
 
 Related: Can Tylenol Cause ADHD? 
 
 British doctors set out to find out more, studying the records of more than 7,700 women who took part in a study when they were pregnant in the early 1990s. 
 
 About half used acetaminophen, also called paracetamol, when they were pregnant. And while just 5 percent of children had behavioral problems at 6 or 7 years old, those who did were more likely to have been born to moms who remembered having used acetaminophen while pregnant, Evie Stergiakouli of the University of Bristol and colleagues reported. 
 
 “Maternal prenatal acetaminophen use at 18 weeks of pregnancy was associated with higher odds of offspring conduct problems and hyperactivity symptoms while maternal acetaminophen use at 32 weeks of pregnancy was associated with higher odds of offspring having emotional symptoms conduct problems hyperactivity symptoms and total difficulties,” the researchers wrote in the Journal of the American Medical Association’s JAMA Pediatrics. 
 
 “Children exposed to acetaminophen prenatally are at increased risk of multiple behavioral difficulties.” 
 
 “Children exposed to acetaminophen prenatally are at increased risk of multiple behavioral difficulties, and the associations do not appear to be explained by unmeasured behavioral or social factors linked to acetaminophen use insofar as they are not observed for postnatal or partner’s acetaminophen use," they added. 
 
 Dr. Hal Lawrence, CEO of the American College of Obstetricians and Gynecologists, said pregnant women shouldn’t worry. 
 
 “ACOG and ob-gyns across the country have always identified acetaminophen as one of the only safe pain relievers for women during pregnancy,” he said in a statement. 
 
 Related: Studies Find Tylenol/ADHD Link 
 
 “This new study, and other studies that have been conducted in the past, show no clear evidence that proves a direct relationship between the prudent use of acetaminophen during any trimester and developmental issues in children.” 
 
 While acetaminophen is considered a very gentle drug, it is not harmless. Large doses can cause liver damage and even kill. The Food and Drug Administration has asked drug companies to limit how much they put into products. 
 
 The researchers did try to address some of the questions doubters had. They asked the women, for instance, about symptoms that may have caused them to take pain medication. Infections such as influenza can affect brain development — for instance, they are linked to autism. It’s one of the many reasons pregnant women are urged to get flu shots. 
 
 But the surveys didn’t ask one key question, which is how often or at what doses the women took the pills. If the risk of behavior problems went up the more often women took the pills, that would be more of a smoking gun. 
 
 “This is all critical information that is missing in order to begin to ascertain a cause and effect,” Lawrence said. 
 
 “Patients should not be frightened away from the many benefits of acetaminophen. However, as always, any medication taken during pregnancy should be used only as needed, in moderation, and after the expectant mother has consulted with her doctor.” 
 
 “ ACOG and ob-gyns across the country have always identified acetaminophen as one of the only safe pain relievers for women during pregnancy.” 
 
 British experts agreed. 
 
 “It is important to highlight that from these results we cannot determine a direct link between paracetamol usage and any behavioral problem,” said Dr. Tim Overton, spokesman for the Royal College of Obstetricians and Gynaecologists. 
 
 "Women should not be alarmed by the results of this study and we recommend that pregnant women continue to follow current guidance and take the lowest effective dose for the shortest possible time when necessary." 
 
 The researchers say that given how common acetaminophen use is, that women should be aware of the findings. They say there are potential explanations of how pain pills might affect a developing fetus. 
 
 "The mechanism might involve disrupted endocrine function, which is important for neurodevelopment," they wrote. 
 
 Behavioral problems such as attention deficit hyperactivity disorder (ADHD) are being diagnosed more frequently. More than 10 percent of U.S. children, or about 5.8 million kids aged 5 to 17 years old, are now diagnosed with ADHD. ||||| Importance Acetaminophen (paracetamol) is used by a large proportion of pregnant women. Research suggests that acetaminophen use in pregnancy is associated with abnormal fetal neurodevelopment. However, it is possible that this association might be confounded by unmeasured behavioral factors linked to acetaminophen use. 
 
 Objective To examine associations between offspring behavioral problems and (1) maternal prenatal acetaminophen use, (2) maternal postnatal acetaminophen use, and (3) partner’s acetaminophen use. 
 
 Design, Setting, and Participants From February 2015 to March 2016, we collected and analyzed data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a prospective birth cohort. We studied 7796 mothers enrolled in ALSPAC between 1991 and 1992 along with their children and partners. 
 
 Exposures Acetaminophen use was assessed by questionnaire completion at 18 and 32 weeks of pregnancy and when the child was 61 months old. 
 
 Main Outcomes and Measures Maternal reports of behavioral problems using the Strengths and Difficulties Questionnaire (SDQ) when the children were 7 years old. We estimated risk ratios for behavioral problems in children after prenatal, postnatal, and partner’s exposure to acetaminophen and mutually adjusted each association. 
 
 Results Maternal prenatal acetaminophen use at 18 (n = 4415; 53%) and 32 weeks of pregnancy (n = 3381; 42%) was associated with higher odds of having conduct problems (risk ratio [RR], 1.42; 95% CI, 1.25-1.62) and hyperactivity symptoms (RR, 1.31; 95% CI, 1.16-1.49), while maternal acetaminophen use at 32 weeks was also associated with higher odds of having emotional symptoms (RR, 1.29; 95% CI, 1.09-1.53) and total difficulties (RR, 1.46; 95% CI, 1.21-1.77). This was not the case for maternal postnatal (n = 6916; 89%) or partner’s (n = 3454; 84%) acetaminophen use. We found the associations between maternal prenatal acetaminophen use and all the SDQ domains unchanged even after adjusting for maternal postnatal or partner’s acetaminophen use. 
 
 Conclusions and Relevance Children exposed to acetaminophen prenatally are at increased risk of multiple behavioral difficulties, and the associations do not appear to be explained by unmeasured behavioral or social factors linked to acetaminophen use insofar as they are not observed for postnatal or partner’s acetaminophen use. Although these results could have implications for public health advice, further studies are required to replicate the findings and to understand mechanisms. ||||| (CNN) Women who take acetaminophen during pregnancy are more likely to have a hyperactive child, according to a new study. Prenatal exposure to the medication was associated with a higher risk of having children who exhibit emotional or behavioral symptoms, the researchers said. 
 
 Acetaminophen, also known as paracetamol, relieves pain and fever and is the active ingredient in Tylenol and hundreds of over-the-counter and prescription medicines, says the Food and Drug Administration website . More than half of all pregnant women in the United States and Europe use acetaminophen, which is also found in medicines for allergies, colds, flu and sleeplessness, according to the authors of the study published in JAMA Pediatrics 
 
 "Acetaminophen is considered safe to use during pregnancy," said Evie Stergiakouli, lead author. She explained that, as with any medication used by mothers-to-be, it should be used only when necessary. A woman and her doctor need to carefully weigh the risks of not treating fever or pain against potential harm to the baby. 
 
 Safety questioned 
 
 On its website, the FDA says it has reviewed previous studies exploring prenatal use of acetaminophen and the risk of attention deficit hyperactivity disorder in children. But "potential limitations" in the design of these research studies prevent the FDA from "drawing reliable conclusions." 
 
 To learn more about acetaminophen and pregnancy, Stergiakouli and her colleagues used data from the Avon Longitudinal Study of Parents and Children , an ongoing study from the University of Bristol in the UK charting the health of 14,500 families. 
 
 Stergiakouli and her colleagues discovered that more than half the mothers (4,415 women or 53%) reported using acetaminophen at 18 weeks of pregnancy, while fewer than half (3,381 women or 42%) reported using it at 32 weeks. Post-natally, a total of 6,916 mothers (89%) and 3,454 partners (84%) used acetaminophen. 
 
 Importantly, just 5% of children displayed any behavioral problems by age 7. 
 
 The researchers then looked at other prenatal factors that might contribute to attention issues in a child, including smoking, alcohol use, socioeconomics and genetics. Factoring these into their analysis, 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. 
 
 "It is important to note there are no studies demonstrating a causal link between acetaminophen use during pregnancy and adverse effects on child development," said Marc Boston, a spokesman for McNeil Consumer Healthcare, the maker of Tylenol. 
 
 He added that the researchers themselves stated that "further studies are required" to determine the cause of the link between behavior problems and prenatal exposure to acetaminophen. 
 
 Dr. Hal C. Lawrence, CEO of the American College of Obstetricians and Gynecologists , echoed this concern, noting that the current study did not examine significant details, such as the exact dose taken or the reasons why a mother needed to take medication. 
 
 "Behavioral disorders are multifactorial and very difficult to associate with a singular cause," Lawrence said. "The brain does not stop developing until at least 15 months of age, which leaves room for children to be exposed to a number of factors that could potentially lead to behavioral issues." 
 
 Pain management during pregnancy 
 
 "Minor aches and pains (e.g. headaches or mild backache), are common in pregnancy and often are a reason for patients to take acetaminophen," said Dr. Aisling Murphy, assistant clinical professor at UCLA Obstetrics and Gynecology . "The practice is very common." 
 
 Murphy said she suggests her patients start with other pain relief methods, such as hot packs, cold packs or massage. Generally, the advice given by UCLA's medical school is to avoid any unnecessary medications, including acetaminophen, during pregnancy and, when necessary, to take only the minimum effective dose, she said. 
 
 In the United States, an estimated 5.1 million children between the ages of 4 and 17 have ADHD, though nearly 11% of kids -- 6.4 million -- have ever been diagnosed with ADHD, according to the Centers for Disease Control and Prevention. 
 
 "The takeaways here are that physicians should not change clinical practice until definitive prospective research is done and, most importantly, patients should not be frightened away from the many benefits of acetaminophen," said Lawrence. 
 
 "This is actually the fourth major study to find acetaminophen use during pregnancy associated with neuro-development of the child," said Michele Marcus, a professor at Emory University Schools of Public Health & Medicine, explaining that she used the word "associated" because there are many reasons that acetaminophen use might not actually cause the behavior problems. Marcus, who is unaffiliated with the study, cited two main limitations of the study, including Lawrence's criticism that dosages were not reported. Another drawback, she said, was the fact that each child's behavior was assessed by the parents. 
 
 Strengths of the study included the fact that it drew on a large population and that the authors examined some genetic factors, which could not explain the behavior problems, Marcus noted. This left the authors to hypothesize prenatal brain development may have been influenced by hormones that had been disrupted by the drug. 
 
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– A popular medication among pregnant women is linked to higher rates of hyperactivity in children, according to a study published Monday in JAMA Pediatrics. CNN reports acetaminophen is found in Tylenol, as well as cold, flu, and allergy medicines. The study's author, Evie Stergiakouli, says it's "considered safe to use during pregnancy." In fact, acetaminophen is one of the few pain relievers that is considered safe for pregnant women, according to NBC News. That may explain why the study of nearly 7,800 women in the US and Europe found that more than half reported using acetaminophen while pregnant, mostly as a treatment for pain or fever. The study found women who reported using acetaminophen at 18 weeks of pregnancy were more likely to have children with conduct problems and hyperactivity. Women who reported using it at 32 weeks, were more likely to have children with hyperactivity and emotional and conduct problems. Still, only 5% of the children in the study were shown to have any such problems. And medical experts say women shouldn't worry yet and should keep using acetaminophen as directed by their doctors. A spokesperson for the company that makes Tylenol points out the study doesn't show a causal relationship between acetaminophen and hyperactivity.