Other risk factors are infections in the mom and certain structural defects in the uterus and the cervix. Then there are a bunch of risk factors that are associated with preterm birth but don't necessarily cause preterm birth. Those include women who smoke during pregnancy, women who are at the extremes of weight (either underweight or very overweight), African-American women (for reasons which I wish we knew but don't), women of low socioeconomic status, and women with certain unhealthy lifestyles that involves alcohol abuse and illicit drug use.
Certainly any underlying health problem can increase risk; hypertension and diabetes are the most common conditions associated with preterm birth, but then other things like autoimmune disorders are associated with an increased risk of preterm birth. Then there are less common problems, like women who have specific bleeding disorders.
There's a lot that a woman can do to reduce her risk of having a premature baby, even though that doesn't guarantee she won't have one. Certainly before pregnancy is the best time to detect and treat any kind of underlying health problem, such as diabetes, weight problems, smoking or hypertension. So "preconception" health and health care is very important. Once a woman is pregnant, she can maintain a healthy lifestyle, have good prenatal care, be screened for underlying medical conditions.
The signs and symptoms of preterm labor are largely the same as those of normal labor, including contractions, changes in vaginal discharge or vaginal bleeding, and lower back pain. Sometimes it's subtle, so it's hard to recognize, or it's just so unexpected, it's not necessarily connected with any risk of preterm delivery. But even when they have those signs and symptoms, they may not recognize them or seek medical help.
She should contact her obstetrical provider immediately, and if she can't get in touch with that person, she should go to a hospital or emergency service to be checked. Sometimes it's false labor, and she can be examined and reassured and sent home. But if it's real, then there are things that can be done to improve the outcome of her and the baby. For example, if she has an infection, the doctor can treat the infection with antibiotics.
Usually the woman would be given tocolytics drugs to help delay delivery for anywhere from one to seven days, usually. And then that would give her time to be treated with antibiotics or whatever, for other kinds of problems such as an infection. If the baby is very preterm, the mother may be given an injection of steroids which can help increase the maturation of the baby's lungs because the lung maturation takes a couple of days with the treatment.
Progesterone is one of the hormones that helps maintain a pregnancy, and it's known that levels go down before delivery. That's why progesterone has been tried to prevent prematurity. But we don't really know if that's how progesterone is working. It may have to do with reducing the stretch effects on the uterus and/or the softening of the cervix that contribute to the onset of labor.
In a recently conducted multi-center trial of progesterone, women who had had a previously preterm birth were given weekly injections of progesterone. The women who received the progesterone had about a 30 percent decrease in their rate of premature delivery, and that translates into a big impact in terms of the length of gestation and the effect on the health of the babies who are born.
In response to that study and another one that's related, the American College of Gynecologists came out with clinical guidelines in November. They state that for those women who have had a previous preterm delivery, it appears that progesterone treatment may be effective for decreasing their risk of having another preterm delivery. Who would respond to the progesterone and who wouldn't and the way to deliver the progesterone still needs to be investigated.