Understanding Stillbirths

Stillbirths occur in 1 in every 160 United States deliveries. The experience is a devastating one for the women and for their families and still, no one really understands why stillbirths happen. The American College of Obstetricians and Gynecologists (ACOG) hopes to work toward reducing the number of stillbirths by gaining a greater understanding of stillbirth—why it happens, and who’s at risk.

To that end, ACOG issued a set of guidelines on clinical management for stillbirths. The guidelines are a review of all that is known about stillbirth and emphasizes that doctors must be vigilant to gather data on such events. The March 2009 issue of Obstetrics & Gynecology contains the published guidelines.

Grim Picture?

Stillbirth is still all too common a tragedy and is defined as fetal death occurring at 20 weeks or more into a pregnancy. Earlier fetal deaths are considered to be miscarriages. An approximate 25,000 stillbirths are reported each year, representing 60% of all perinatal deaths in the United States. But the picture is not quite a grim as it sounds.

There has been a decrease in stillbirths over the last several years and this suggests doctors are closer to an understanding of the causes and risk factors for the catastrophe of stillbirth. In 2004, for instance, the U.S. stillbirth rate was 6.2 for every 1,000 births. This was down from 6.4 for every 1,000 in the year 2002. The rate for early stillbirth, at between 20-27 weeks of pregnancy, has remained somewhat stable since 1990 at the approximate rate of 3.2 for every 1,000 births, while late stillbirths, from 28 weeks gestation or more, has gone down from 4.3 to 3.1 in every 1,000 births.

Risk Factors

There are four common risk factors for stillbirth: no previous births, obesity, advanced maternal age, and non Hispanic black race. Black women are at the greatest risk for stillbirth with the rate at 11.25 in 1,000 births as compared with all other races that have rates of fewer than 6 in every 1,000 births. The high rate of stillbirth seen in black women seems to bear no linkage to the level of prenatal care received. Experts instead attribute this disparity to the higher rates of hypertension, diabetes, premature rupture of the membranes and placental abruption in black females.

Diabetes and hypertension are medical conditions that are often found to coexist with pregnancy and both of these conditions are known risk factors for stillbirth. Diabetes appears to increase the risk for stillbirth by double to five times the normal risk. Obesity is known to be a risk factor for both miscarriage and stillbirth. In those women with a body mass index (BMI) of 30-39.9, the rate of stillbirth goes up to 8 in every 1,000 births. In women with a BMI of greater than 40, the rate shoots up to 11 in every 1,000 births.

Another risk factor for stillbirths is multiple pregnancies. A pregnancy consisting of two fetuses or more has a rate of stillbirth four times greater than that of a single fetus pregnancy. Women aged 35 and up are also at greater risk for stillbirth and those having a first baby have a greater risk than those women who have already born at least one child.

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