Women who are in the habit of popping up over-the-counter painkillers during pregnancy could increase the risk of their daughters entering puberty earlier than normal, warns a research.

The study observed that girls whose mothers consumed paracetamol during pregnancy exhibited pubertal symptoms such as breasts, pimples, menstruation, hair growth in places and unpredictable mood swings, on average, three months earlier, than the normal. These symptoms were visible even more earlier if the mother took paracetemol for more than 12 weeks during pregnancy.

"While entering puberty one-and-a-half to three months earlier may seem unimportant, when taken together with the frequent use of paracetamol during pregnancy, our findings ought to make people take notice," said Andreas Ernst, a post-doctoral student from Aarhus University in Denmark. "Our results are certainly not the decisive factor that should change current practice, but the perception of paracetamol as 'the safe and harmless choice' during pregnancy ought to be challenged," Ernst said.

For the study, published in the journal American Journal of Epidemiology, the researchers examined around 100,000 women who provided detailed information about their use of paracetamol three times during their pregnancy. A total of 15,822 children -- 7,697 boys and 8,125 girls -- born to these mothers were followed from the age of 11 and throughout puberty with questionnaires about several different aspects of their development.

The results revealed a tendency towards slightly earlier female pubertal development attainment with increasing number of weeks of exposure. "We found a 'dose-response' correlation. That is to say, the more weeks with paracetamol during pregnancy, the earlier puberty in girls, but not in boys," said Ernst.

However, male pubertal development had no strong association with mother's paracetamol exposure. As earlier pubertal development has been tied to an increased risk of more frequent and serious diseases in adulthood such as obesity, diabetes, cardiovascular diseases and testicular and breast cancer, it is important to identify possible causes of early puberty so we can prevent this development, Ernst said.