Obesity raises the chances of complications and medical interventions in childbirth, but a new study indicates that the risks are not the same for all obese women.
The researchers, from Oxford University, say that for otherwise healthy women, the increase in risk with obesity may not be as great as previously suspected. "The increased risk was fairly modest for obese women who did not have conditions such as high blood pressure, diabetes or a previous caesarean section, and the risks were quite low if the woman had given birth previously," says lead researcher Jennifer Hollowell.
While around half of obese women giving birth in obstetric units have medical problems or pregnancy complications, the new study focused on women who were obese but otherwise healthy when they went into labor.
The researchers say the risks of complications during childbirth did go up with increasing body mass index among these healthy women, but the increase was modest.
However, whether a woman has had a previous baby plays a larger role in influencing the chances of needing hospital care. Fifty-three percent of women of normal weight having their first baby had an intervention or a complication at birth. The figure was 21 percent for very obese but otherwise healthy women having a second or subsequent baby.
"This finding does highlight a possible anomaly in the guidance given to women on where to give birth," said Hollowell. Currently, first-time mothers with low-risk pregnancies can plan to have their child in hospital, at home, in a free-standing midwife-led unit or an alongside midwifery unit connected to a hospital. However, current guidelines suggest all women with a BMI over 35 should be advised to have the birth in an obstetric unit to reduce risk.
"We think that the guidelines might need to be reviewed to take account of this more nuanced understanding of the effect of obesity," says Hollowell. "We think it's worth considering whether it might be safe to allow some healthy obese women having a second baby the option of a birth in an alongside midwifery unit where obstetric and neonatal care is available on site if needed."
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Source: University of Oxford