A new study suggests that women who had one stillbirth have four times more likely to experience another stillbirth.

A stillbirth occurs when the fetus dies after completing 24 weeks of pregnancy; any death earlier than that is considered a miscarriage. About half of the deaths are linked to placental complications, while other causes are due to birth defects and poor health of the mother. About one in 160 pregnancies in the United States lead to stillbirths.

Mothers often feel devastated after the loss of a child and worry about having another one. Although that possibility remains, 97.5 percent of the pregnancies result in the live birth of a healthy baby.

"Despite the higher risk of recurrence, most pregnancies following a stillbirth will progress normally and end in the birth of a healthy baby," Sohinee Bhattacharya, study leader and a lecturer at the Institute of Applied Health Sciences at the University of Aberdeen in Scotland, said to HealthDay News.

The researchers reviewed 16 studies that involved 3.5 million pregnant women from eight different countries. The analysis showed that 0.7 percent of the women had stillbirths. Of those who had stillbirths and attempted a second pregnancy, 2.5 percent experienced another stillbirth.

However, having a live birth during the first pregnancy did not reduce the risk of a stillbirth on the subsequent pregnancies because 0.4 percent had stillbirths after a live birth.

The study published in the June 24 issue of BMJ concluded that one stillbirth increases the risk of another one by four times.

The authors admitted that further study is needed to explain the cause of subsequent stillbirths. They also recognized that some of the studies they reviewed do not have a standard definition of stillbirth; some started counting from 28 weeks instead of 24 weeks.

"Standardized definitions are vitally important for us to make any progress in stillbirth research," Bhattacharya told MedPage Today.

The researchers plan to continue their study by getting records from birth registries worldwide and analyzing the data based on the standard definition of a stillbirth. As for those who have experienced stillbirths, the researchers recommend a regular and early consultation with their doctors to lower the risk of another stillbirth.