Risk of preterm delivery could be reduced with the help of progesterone gel, says a new study. The exact cause of preterm birth is often unclear. Studies have shown that women with short cervix, history of preterm delivery and women pregnant with twins or triplets have a higher risk of experiencing preterm labor.
The National Institute of Health study, reported online in Ultrasound in Obstetrics and Gynecology, says that progesterone might benefit women with short cervix who are more likely to give birth before the 33rd week of pregnancy. Infants born too early have an increased risk of long-term health problems. They might develop learning disabilities, blindness, deafness, cerebral palsy and breathing problems. Preterm infants have a higher risk of dying before their first birthday.
According to international agencies, in 2005, more than 12 million preterm births occurred worldwide. To reduce the incidence of preterm birth and the health problems it entails, researchers from 44 health care centers, from around the world, in association with Eunice Kennedy Shriver National Institute of Child Health and Human Development conducted the study.
More than 450 pregnant women participated in the study. The length of the cervix of the subjects was between 1cm and 2cm. The cervix length is measured with the help of transvaginal ultrasound. Earlier studies have shown that women with cervix length less than 2.5cm are 50 per cent more likely to give birth at an early stage.
Progesterone, a prominent pregnancy hormone, is secreted by the ovaries. It thickens the endometrium or the lining of the uterus. The endometrium starts to thicken after ovulation when the secretion of progesterone escalates. The thickness of the endometrium is directly proportional to the progesterone level in the body. A thick endometrium helps the fertilized egg to implant in the uterus.
Secretion of this pregnancy hormone continues throughout pregnancy. From the 8th week of pregnancy, the placenta starts producing larger quantities of progesterone. It is needed for supporting healthy pregnancy. The size of the cervix determines the progesterone level. Short cervix is a sign of progesterone deficiency. During pregnancy, the cervix dilates by 3.8cm up to 5cm. The cervix lengthens to accommodate the growing fetus. A short cervix is a warning sign of premature labor.
Researchers found that pregnant women who were treated with vaginal progesterone gel between the 19th and 35th week of pregnancy were almost 45 per cent less likely to deliver earlier than women who received placebo gel. Only 5.1 per cent women who received progesterone gel gave birth before the 28th week of pregnancy, whereas 10.3 per cent women who were given a placebo gel delivered a preterm infant before the 28th week of pregnancy.
The study further showed that infants born to women who received progesterone gel had lower risk of respiratory distress syndrome, a common health problem among preterm infants. Usually pregnant women diagnosed with short cervix during the second trimester of pregnancy are recommended bed rest.
Occasionally, it is treated with the aid of a controversial surgical procedure, called cervical cerclage. The new study shows that progesterone therapy might be a safer alternative for reducing spontaneous birth before the completion of the normal gestation period.