Jefferson doctor says common test could mean more precise due date

PHILADELPHIA (WPVI) -- If you are expecting a baby, you know figuring out the due date isn't always easy or accurate.

Estimates can be off by two to three weeks, either early or late.

And only 5-percent of women actually deliver on their due date.

But a doctor at Jefferson University Hospital says a routine screening late in pregnancy could narrow down that date.

Doctor Vincenzo Berghella, senior author on the study, says it shows that trans-vaginal ultrasound at 37-39 weeks to measure the length of the cervix can accurately predict the chances a woman will deliver within the next week.

He told Action News a better way of knowing is long overdue.

"You can tell them if there's a fetal anomaly to a very good degree of certainty, you can now tell in terms of genetics if the baby's doing Ok or not, you can almost do a whole genome on a baby before the baby's born, but if she comes in and says, OK, I'm 8 months, or 9 months along, am i going to deliver this week or next week, we still look dumbfounded, so to speak," he says.

"Because we have no idea when she's going to deliver," he continued.

Transvaginal ultrasound measures the length of the cervix - the shorter the length, the more likely labor is imminent.

"It's very safe, we have no incidence of more infections or problems. it takes less than 5 minutes," says Dr. Berghella.

The doctor says transvaginal ultrasound is commonly used at about 20 weeks to check the risk of premature birth.

Doing it again later in pregnancy can show whether the body is getting ready for delivery.

Getting a more accurate due date is important for several health reasons, including determining whether a woman who had one C-section will need another.

Dr. Berghella says it can also help women prepare for work leave, know whether it's safe to travel, or make contingency plans for taking care of older children.

"This is something that women want, something that's on their mind probably starting in the second half, or at least the last third of their pregnancy," he says.

"Everybody's asking them when they;re going to deliver. And it's been frustrating, to tell you the truth, for patients, but also for doctors, not to be able to predict," he noted.