For U.S. moms , the typical time between pregnancies is about 2½ years but nearly a third of women space their children too close , a government study shows . Experts say mothers should wait at least 18 months to give their body time to recover and increase the chances the next child is full-term and healthy . The study released on Thursday by the Centers for Disease Control and Prevention found that about 30 percent of women who 'd had a child became pregnant again within 18 months . Dangerous pregnancy : The study released on Thursday by the Centers for Disease Control and Prevention found that about 30 percent of women who 'd had a child became pregnant again within 18 months . Second baby : For U.S. moms , the typical time between pregnancies is about 2½ years but nearly a third of women space their children too close , a government study shows . 'That is actually pretty high and very problematic , ' said Heike Thiel de Bocanegra , a reproductive health researcher at the University of California , San Francisco . She was not involved in the new study . The report is based on 2011 birth certificates from 36 states and the District of Columbia , representing about 83 percent of the nation 's births that year . It was the first such report by the CDC so researchers do n't know if pregnancy spacing has changed over time . The study found that the median time to next pregnancy was 2 years , 5 months . About half fell in the 18 months to 5 year range . About 20 percent had babies more than 5 years apart . White women had the shortest spacing — about 2 years , 2 months on average . Black and Hispanic women typically waited 2½ years or longer . The older the mom was , the longer the spacing between a birth and her next pregnancy . Data : The report is based on 2011 birth certificates from 36 states and the District of Columbia , representing about 83 percent of the nation 's births that year . Of course , miscarriages , illnesses or other factors can affect a couple 's plans . Lhamo Ellin of New York had her daughter about 12 years after her son . ' I tried . It did n't happen , ' said Ellin . She works as a nanny in a Brooklyn neighborhood that is a magnet for young families , where she said siblings seemed to be about three to five years apart . New Yorker Reis Goldberg and his wife had twin boys and then a daughter 3½ years later . 'As soon as we got the twins under control , we were ready to have another one , ' he said . Goldberg , who is only about a year younger than his brother , agreed with the experts . 'Second kid suffers . A lot runtier . He was like double my size when I was younger , ' he said . Racing for a child : White women had the shortest spacing — about 2 years , 2 months on average wheras black and hispanic women typically waited 2½ years or longer .
For U.S. moms , the typical time between pregnancies is about 2½ years . Experts say mothers should wait at least 18 months to give their body time to recover and increase the chances the next child is full-term and healthy . TL;DR The average American woman has a baby every 2.5 years, according to new research from Johns Hopkins University School of Public Health.