As many as two in three expectant mothers don't know how much weight is appropriate to gain during pregnancy, according to new research out of Australia.
The study, led by Susie de Jersey from Queensland University of Technology's Institute of Health and Biomedical Innovation, found a third of women surveyed gained too much weight during pregnancy, while another third struggled to gain enough weight.
"The majority of the women in the study knew healthy eating was important, but very few could identify how much they should be eating from different food groups, particularly fruits and vegetables," said de Jersey, who is also a senior dietician at the Royal Brisbane and Women's Hospital.
"Most women said they also didn't know the recommended amount of weight they should gain during pregnancy and reported very limited advice about healthy weight gain."
She added that fewer than half of the study's participants viewed exercise during pregnancy as very important, possibly due to misconceptions that physical activity is not safe for mothers-to-be.
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The study, published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, also showed that more than half of the women who were overweight before getting pregnant gained too much maternity weight, compared to only a third of their trimmer counterparts.
She noted pregnant women who gain too much, or too little, weight face greater health risks, as do their babies.
According to women’s health experts, the amount of weight a woman should gain during pregnancy depends on her body mass index (BMI) prior to conception. The higher the BMI, the less weight she should gain.
BMI is calculated by dividing weight in pounds by height in inches squared and then multiplying that figure by 703. For example, a person who is 5-feet-5-inches tall (65 inches) who weighs 150 pounds has a healthy BMI of 24.96 (150 divided by 65, squared, times 703 equals 24.96). The Centers for Disease Control and Prevention provides a BMI calculator and information at cdc.gov/bmi.
A woman with a healthy BMI (between 18.5 and 24.9) should gain 25-35 pounds during pregnancy, while a woman with a BMI below 18.5 should gain as many as 40 pounds, and a woman with a BMI above 30 should gain no more than 20 pounds.
"There are a lot of psychosocial factors in play — many of these women may have more negative experiences from trying to control their weight in the past," de Jersey said. "The reality is that some women find it easier to control their weight than others both before and during pregnancy.
"We know that we need to acknowledge their prior experiences and work with them to improve their confidence and to help them engage in healthy behaviors."