In a study published Tuesday in the journal Diabetes Care, Toronto researchers found women who maintained excess pounds between three and 12 months postpartum had elevated risk factors for diabetes and cardiovascular disease.
"What we saw here was the women who didn't lose weight had higher blood pressure, higher levels of LDL — or bad cholesterol — greater resistance to insulin and lower levels of a particular hormone that is believed to be protective against diabetes and heart disease," said principal researcher Dr. Ravi Retnakaran.
"The adverse consequences of retaining excess weight from your pregnancy may develop a lot earlier than we expected, within the first year," said Retnakaran, an endocrinologist at Mount Sinai Hospital.
To conduct the study, researchers monitored 305 obstetrical patients throughout pregnancy and during the year following delivery.
About three-quarters of the women lost at least some of their baby weight by one year. Tests at three and 12 months postpartum showed their cholesterol, blood pressure and other cardiometabolic measures were at healthy levels.
But one-quarter of women who did not trim pregnancy weight or even added extra pounds during that period showed elevated levels at 12 months postpartum, which had not been present at the three-month mark.
"At this stage in their life, these are women of child-bearing age. They're not that old. They're very healthy," said Retnakaran, adding that subtle changes in their blood pressure and other measures may not immediately raise a red flag for doctors.
"The levels in young women at risk in whom these risk factors are going to be relevant to their potential, ultimate development of heart disease, those levels when they're 25, 26 are not going to be the kind of levels that are going to cause their physician to take notice," he said.
"But you give them those levels compared to their peers and give them that exposure for 20 years and now you've got diabetes and heart disease."
The effects from retaining weight post-delivery are similar to those experienced by women who suffer gestational diabetes during pregnancy, which research has shown puts them at greater risk for heart disease later in life.
"It's the same concept and a very important concept because it emphasizes that ... this is the time when you want to intervene," Retnakaran stressed.
"But in order to identify those at risk, you're actually looking for subtler changes than if you were looking at a 65-year-old man with a BMI (body mass index) of 30."
Still, simple lifestyle choices appear to make a difference: new moms who were more physically active, particularly those who engaged in sports, had a significantly lower likelihood of carrying extra weight between three and 12 months after giving birth, the study showed.
"That's an encouraging message," said Retnakaran, suggesting that this nine-month window is a critical period for women to shed at least some of their pregnancy weight with healthy lifestyle choices.
Dr. Andreas Wielgosz, a cardiologist at the University of Ottawa, said the study focuses on an issue of "great interest and potential significance."
"So many women relate weight gain to pregnancy, and we're of course always concerned about the consequences of weight gain, regardless of when it occurs," said Wielgosz, a spokesman for the Heart and Stroke Foundation, which was not involved in the study.
Women and their doctors need to pay attention to lifestyle elements such as exercise, a healthy diet and getting adequate sleep, which can help get rid of baby weight and reduce the risk of eventual heart disease and diabetes, he said.
"I think it's a wake-up call for both the physicians and for the women themselves."
Among study participants, half were first-time mothers, while most of the rest had given birth to their second baby. About five per cent of the women already had two or more children.
While the study didn't look at weight gain carried over from multiple pregnancies, Retnakaran said the adverse effects on blood pressure and other cardiometabolic disease markers may indeed be cumulative.
"So would the same thing happen with your next pregnancy if you don't lose weight? You would anticipate that it probably does, and each time your risk factor profile is getting worse and worse," he said. "By that second pregnancy, if you didn't lose it after the first pregnancy, you're already at a more adverse risk profile at the outset.
"You're starting from a worst place before the next pregnancy."
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