Purpose of dating scan
Cervical checks, in which a doctor manually feels the length and softness of the cervix with his or her fingers, are typically not very reliable, Berghella said.
However, studies have shown that women who have a short cervix, less than 1 inch (2.5 centimeters) long, as measured on ultrasound scans during mid-pregnancy, are at high risk for preterm birth.
That made researchers wonder whether similar scans could be predictive during the homestretch of pregnancy.
In late pregnancy, as the body prepares for labor, the cervix — a cone-shaped organ that sits between the uterus and the vagina — begins to flatten out.And hospitals could make arrangements to have more staff on hand if they know lots of deliveries are imminent in the next week, Berghella said.Sometimes, women have a medical condition that necessitates delivering their baby soon, but not necessarily immediately.He found that among the women whose cervix was more than 1.18 inches (3 cm) long at the time it was measured, less than 50 percent of these women delivered within a week.By contrast, among the women whose cervixes were less than 0.4 inches (1 cm) long, 85 percent delivered within a week, the researchers reported today (Oct.