Nearly a quarter of all mothers were obese at the beginning of their pregnancy, according to a new study from the Centers for Disease Control and Prevention (CDC). That rate has risen in recent decades, and as evidenced by previous research, could lead to a growing population of mothers who will remain obese even after giving birth.

There are a range of adverse health effects that come with pre-pregnancy obesity. The bulk of these are particularly dangerous because of how the growing fetus obtains nutrients from the mother’s body. When that body is underperforming, or otherwise struggling to maintain homeostasis, the fetus suffers. The child may be delivered too early, be underweight, or face greater risks for infant mortality. Moreover, children born to an overweight mother are three times more likely to be overweight by the time they reach their 7th birthday than children born to mothers of a healthy weight.

After decades of increasing maternal obesity pre-pregnancy, the CDC’s latest study confirms a continuing upward trend. An analysis of 2011 data, the most recent year the data is available, shows that 23.4 percent of mothers were obese. In 1993, the rate was 13 percent. In 2003, it had jumped to 22 percent. Now health care professionals and researchers alike are striving to get the word out about maternal health pre-pregnancy.

"It's important for women to normalize their body weight before they become pregnant,” Dr. Jill Rabin, chief of ambulatory care, obstetrics, and gynecology at Long Island Jewish Medical Center, told Live Science. Doing so would be in both the mother’s and child’s best interest, Rabin added.

Women who carry a pregnancy to term while overweight face an increased risk for diabetes (which, in itself, carries an added risk pre-pregnancy of stillbirth and infant death), Caesarean delivery, and preeclampsia (high blood pressure). Meanwhile, the mother passes on a risk of delivering her baby stillborn, prematurely, and in some cases even overweight itself. According to the Institute of Medicine (IOM), women who are already obese going into their pregnancy should stick to a strict plan when it comes to how much additional weight they can safely gain.

Healthy American women at a normal weight for their height, measured as body mass index (BMI of 18.5 to 24.9) should gain 25 to 35 lbs. during pregnancy, a 2009 IOM report states. Underweight women (BMI less than 18.5) should gain more, 28 to 40 lbs., and overweight women (BMI of 25 to 29.9) should gain less, 15 to 25 lbs. These are the same standards outline in the 1990 version of the guidelines; however, they reflect the ever expanding American waistline, as they now include a guideline for women with a BMI over 30. Women in this range should gain 11-20 lbs. According to a 2012 study, avoiding these guidelines may pose a greater risk for mothers down the road — even after the baby has been born.

“This report gives women and their health care providers an evidence-based answer to the question of how much weight women should gain during pregnancy," Kathleen Rasmussen, professor of nutrition, division of nutritional sciences at Cornell University, said in the release. "We call on health professionals to adopt these guidelines and help women follow them so that mothers and their children will have the best health outcomes possible.”