An alarming new study finds that women are making a very bad choice after a pregnancy.

About 43 percent of women who quit smoking during their pregnancy went back to cigarettes just six months after the birth of their child, according to a Wiley statement.

Knowing that it’s bad for their babies, women will often quit smoking if they find out they’re pregnant, but they appear to have difficulty kicking the habit for good once the child is born — meaning that newborn could be exposed to second-hand smoke at a very early age.

The findings, published in the journal Addiction, examined 27 trials that attempted to help pregnant women stop smoking. The researchers wanted to see how the women fared six months later, and the results were disappointing. A full 87 percent of women weren’t even successful in stopping smoking during the pregnancy, either because they didn’t try or they tried and failed. And of those 13 percent, nearly half started smoking cigarettes six months later.

Studies show that children exposed to second-hand smoke tend to get sick more often, and their lungs don’t develop as well, leading to more cases of bronchitis and pneumonia. It can also trigger asthma attacks in children.

“Smoking during pregnancy is a major global public health issue: a conservative estimate for the annual economic burden in the UK is £23.5 million and in the US $110 million,” lead author Dr. Matthew Jones said in the statement. “Our report reveals a wide gulf between what pregnant women need to quit smoking and what our healthcare services currently provide.”

The statement adds: “While not smoking during pregnancy is very important, there is an urgent need to find better ways of helping mothers stay of cigarettes afterwards. Approximately 18,887 pregnant smokers in the UK (3% of all maternities) used NHS stop-smoking support in the financial year 2014/15.1,2 This represents a considerable investment.”