The chances of having a miscarriage are about twice as high as the odds of having one during pregnancy, according to a study published in the medical journal Obstetrics & Gynecology.
The researchers looked at the number of women in the U.S. who had been diagnosed with miscarriage in the previous 30 days and found that a woman who had a miscarriage in her first 30 days was five times more likely to miscarry in her second 30 days, the researchers said.
“We did not know the exact timing of miscarriage onset, but the data indicates that a miscarriage is likely to occur between 28 and 48 hours postpartum,” said lead author Jennifer Niebuhr, a clinical professor at the University of Texas Southwestern Medical Center.
The authors also found that the risk of miscarriage was higher among women who had given birth within the previous week.
In fact, the odds were more than twice as great for women who miscarried in the first week of pregnancy compared to women who did not miscarry.
The study is the first to examine the timing of pregnancy miscarriage, Niehrer said.
She hopes it will lead to better ways to track the number and severity of miscarriages in women who are at increased risk for having one in the future.
In a statement, NIEbuhrh said the findings were important to understanding the causes of miscarriage.
“In a country with high rates of preterm births, we have many women with preeclampsia, which can lead to a higher risk of pregnancy loss,” Niec said.
“These results show that if a woman has preeclampia, the risk for miscarriage is twice as likely.”
Read more about pregnancy and miscarriages:A miscarriage is a pregnancy loss, the first of many problems that can lead women to have a miscarriage, said Niebrer.
In the study, Niedersh and colleagues analyzed data from 1,633 women who were diagnosed with preterm birth, a term used to describe pregnancies that begin before 42 weeks of gestation.
Preterm birth has a high risk of complications, such as a low birth weight, high birth weight or low birth size, and a greater risk of death.
The odds of pregnancy-related complications during preterm delivery are about 10 times higher than those in non-preterm birth cases.
The team looked at data from the National Center for Health Statistics and the National Vital Statistics System from 2014 through 2017.
Pre-term birth is more common among white women and is more likely among older women, who tend to have fewer pregnancies.
It is also more common in the South, where it is more prevalent than elsewhere.
Niebrers study did not include women who miscarry while pregnant, but researchers believe the study could help identify women who do miscarry as they get older.
“Our results show a very significant increase in preterm-related mortality risk associated with having a preeclamping condition and not having a preterm pregnancy,” Nieshrer added.
“Preterm-associated mortality has been increasing since the 1990s, but it’s been underreported in the literature.”
The authors say more research is needed to understand the relationship between preeclamptic conditions and miscarriage risk.
The researchers plan to conduct additional studies that look at a range of risk factors for miscarriage, including pregnancy-associated risk factors, maternal age, race, smoking and alcohol consumption.
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