Hot Off The Press

Learn more about PTBi’s most recent advances in prematurity research.

Are women more likely to give birth prematurely in their second pregnancy?

Having a baby preterm or even early term (37-39 weeks of pregnancy) increases the risk of a second preterm birth.

This study compared the length of 163,889 women's first versus second pregnancies, and found that women with a previous preterm birth were more likely to have a subsequent preterm birth (<37 weeks). In fact, any shorter first pregnancy (<40 weeks) increased the risk of a subsequent preterm birth, even if the first pregnancy was “early term” (37-39 weeks). This is the first ever study to report that early term pregnancies are associated with later preterm birth risk, suggesting that there are common risk factors between preterm birth and early term birth. Women giving birth early preterm (<32 weeks) were at the highest risk for a subsequent early preterm birth.

View the August, 2016 study in Obstetrics & Gynecology on Pubmed: Recurrence of Preterm Birth and Early Term Birth
This paper was ranked in the top 1% of all papers published by the journal in the past year, in terms of citations and mentions. It was picked up by 83 news outlets and was #1 of all Ob/Gyn papers in the news during its first week of publication.

Does the length of time between pregnancies matter?

Waiting too long — or not long enough — between pregnancies might increase the risk for preterm birth.

This study used data from one million California women who gave birth between 2007-2010 to examine if the length of time between birth and the next conception — called interpregancy interval (IPI) — is related to preterm birth risk. The study found that women who conceive either less than 11 months or more than 3 years after giving birth are more likely to have a premature baby in their next pregnancy. The lowest risk was for pregnancies spaced 18-23 months apart.

View the November, 2016 study in the British Journal of Obstetrics & Gynecology on Pubmed: Interpregnancy interval after live birth or pregnancy termination and estimated risk of preterm birth- a retrospective cohort study

If preterm babies are smaller or larger than average for their age at birth, are they more likely to develop complications?

A preterm baby's birth weight can provide information about whether he or she might be at risk for complications of prematurity.

This study shows that it is important to consider a baby’s birth weight compared to the average weight for his or her age at birth — which is called gestational age — when evaluating risk for prematurity-related complications. Preterm babies that are small for their gestational age (smallest 10%) and born between 28-38 weeks were more likely to develop complications, whereas preterm babies that are large for their gestational age (heaviest 10%) were not. Larger preterm babies were more likely to survive if born between 25-27 weeks, but less likely if born between 28-31 weeks.

View the November, 2016 study in the Journal of Perinatology on Pubmed: Population-based risks of mortaility and preterm morbidity by gestational age and birth weight

How do mental illnesses, including mood disorders, affect preterm birth risk?

Depression, schizophrenia, or personality disorders are linked to increased risk for delivering preterm.

This study showed that women who have been diagnosed with a mental illness were 1.2 times more likely to give birth preterm than women who have not been diagnosed. The greatest risk was for women with schizophrenia (2.0 times more likely to give birth preterm), major depression (2.0 times more likely) and personality disorders (3.3 times more likely). It is not yet known if the increased risk for prematurity is related to treatment(s) for mental illnesses, or because of the illnesses themselves.

View the October, 2016 study in the American Journal of Obstetrics & Gynecology on Pubmed: Risk of preterm birth by subtype among Medi-Cal participants with mental illness