One in Eight Births Is Preterm

Today, 1 in 8 infants, or about 13%, is born before the usual 40-week gestation period, according to the March of Dimes, compared with 9.4% in 1981. A baby born before 37 weeks of pregnancy is considered a preterm, or premature, birth. Preterm birth is the nation's leading cause of infant death, responsible for more than one-third of infant deaths before age 1, according to the Centers for Disease Control and Prevention.

"The rate of preterm births is going up, and we don't always know why," says Mary Ames-Castro, MD, an Assistant Professor of Obstetrics and Gynecology at the Medical College of Wisconsin. She is one of four perinatologists - specialists in maternal-fetal health - who practice at the Maternal Fetal Care Center, a collaborative effort located within Children's Hospital of Wisconsin.

Sometimes these preterm births are preceded by pregnancy complications that can pose serious threats to the infant's and mother's health. Although preterm births are not ideal, about 25% of them are intentional - that is, medically induced to give mother and baby a better chance of a healthy outcome, she says.

"We induce delivery whenever the mother or baby is under stress. It's a risk-benefit calculation. And one benefit is that, today, many women with health conditions that used to make them high risks for pregnancy are able to carry babies to term or near-term. It's amazing how far prenatal care has come in the past decade or two."

Risk Factors
According to the National Institute of Child Health and Development, health care providers currently have no way of knowing which women will experience preterm labor or deliver their babies preterm. But some factors do place a woman at higher risk for pregnancy complications and preterm delivery. Commonly these include mothers with high blood pressure and gestational diabetes as well as type 1 and type 2 diabetes; and less commonly, congenital heart defects, cancer, HIV, pancreatic and kidney disorders, or sickle cell anemia.

"Extremes of age can also put women at higher risk of complicated pregnancies and babies with birth defects or other anomalies," Dr. Ames-Castro says. Very young teenagers as well as older women are at higher risk of complications, although the risk varies considerably by individual. "Even in these cases," she says, "moms whose pregnancies are carefully monitored and who take care of themselves can have healthy babies."

At the Maternal Fetal Care Center, Dr. Ames-Castro and her fellow perinatologists diagnose and treat women with high-risk complications, often acting in consultation with patients' own obstetricians or other primary care physicians. They also see patients with normal pregnancies. Programs and services include prenatal diagnosis, including first and second trimester screening, other specialized testing, and prenatal surgery.

Parents often choose to deliver at the Froedtert & Medical College Birth Center, located within Children's Hospital, where advanced neonatal care is available immediately if needed. That allows patients whose infants are born with complications to stay in the same building with their newborn. Infants born prematurely might need to be hospitalized for several weeks or more, often in the neonatal intensive care unit, or NICU.

Helping Women with Blood Disorders
Part of the Maternal Fetal Care Center includes a Pregnancy Coagulation Clinic that gives women with clotting and bleeding disorders the best chance of achieving a healthy pregnancy. One of few in the country, the clinic is directed by Randall S. Kuhlmann, MD, PhD, Associate Professor of Obstetrics and Gynecology at the Medical College and Director, Division of Maternal Fetal Medicine.

"It's one of the busiest such clinics in the country," Dr. Ames-Castro says. There, patients with such serious conditions as hemophilia, immune thrombocytopenic purpura, acquired and inherited thrombophilia, deep vein thrombosis and pulmonary embolism are cared for.

Prenatal Diagnosis and Screening
The center also offers genetic testing and counseling, including prepregnancy consultation. "Ideally," Dr. Ames-Castro says, "we prefer that patients with hypertension, seizures or diabetes be screened and counseled before they become pregnant - or, failing that, as early in their pregnancy as possible. We want to make sure conditions such as diabetes are controlled and stabilized, or that a heart defect is repaired, so that the mom's condition is optimal before she gets pregnant."

The center also provides a wide range of ultrasound services, including first trimester scans, detailed fetal anatomy scans, fetal growth scans, second opinion scans for known or suspected fetal abnormalities, biophysical profiles and ultrasound guidance for prenatal diagnostic procedures such as amniocentesis and chorionic villus sampling.

First-trimester screening is performed between 11 and 14 weeks gestation. It presents minimal risk to the mother and baby, and includes an ultrasound measurement and a maternal blood test. The blood test measures the amount of two chemicals in the mother's blood. Different levels of these chemicals can indicate various problems, such as a higher risk for Down syndrome or a chromosomal abnormality called trisomy 18. Most insurance plans will cover the cost of this screening.

In addition, the Maternal Fetal Care Center is the only center in the area to offer sequential screening in the second trimester. This test, which is slightly more accurate than just first trimester screening alone, includes another maternal blood draw, this time looking for four chemicals. Those results are combined with the first trimester screening results to provide the most accurate risk assessment for open neural tube defects, such spina bifida, as well as Down syndrome and trisomy 18.

Hypertension and Diabetes
Dr. Ames-Castro and her colleagues are alert for the more common complications that can stem from hypertension and diabetes. If a pregnant woman experiences a sudden increase in blood pressure after the 20th week, it signals a condition called pre-eclampsia, which can affect the mother's kidney, liver and brain. If left untreated, it can be fatal for the mother or the baby, or both, and can lead to long-term health problems. Eclampsia is a more severe form of pre-eclampsia that can cause seizures and coma in the mother.

Although pre-eclampsia can't be prevented, some women seem to be at greater risk for it, including those who are obese, have diabetes or kidney disease, or are carrying multiple fetuses. If pre-eclampsia develops, the physician may develop a plan to try to prolong the pregnancy to give the fetus more time to grow and mature. At the same time, the health care provider will closely watch the health of the mother for signs that the fetus needs to be delivered right away, even prematurely, if necessary. In fact, the only cure for pre-eclampsia is delivering the fetus.

Another condition that can occur in the second trimester is gestational diabetes, meaning it occurs only during pregnancy and not previously. It affects about 5% of pregnant women, or 1 in 20. Most women who have gestational diabetes give birth to healthy babies, especially when they control their blood sugar, eat a healthy diet, exercise, and keep a healthy weight, Dr. Ames-Castro says. In most women with gestational diabetes, their blood sugar returns to normal after the baby's birth.

As with gestational diabetes, women who had type 1 or type 2 diabetes before they became pregnant can also deliver healthy babies when they keep their blood sugar levels within their target range before and during pregnancy, she says. When diabetes is poorly controlled, however, especially during the first two months of pregnancy, the baby is at risk for severe anomalies, including brain, spine, and heart defects." With obesity increasing among young people, we're seeing more type 2 diabetes pregnant women than before," Dr. Ames-Castro says.

"Medical literature has observed that when babies are diagnosed in utero and delivered at a tertiary care center that offers coordinated care, they do much better. And in situations where the baby may have anomalies or be at risk for pre-term birth, or if the mother has a medical condition, it is better for both to be transported before birth, versus after the baby is born," notes Dr. Ames-Castro.

"Providing coordinated care for mother and baby at one location can have a tremendous impact on outcome."

Barbara Abel
HealthLink Contributing Writer

This article includes information from the March of Dimes, the Centers for Disease Control and Prevention, and the National Institute of Child Health and Development.