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Risk of stillbirth, preterm delivery and fetal growth restriction following exposure in previous birth: systematic review and meta-analysis

Plain language summary from BJOG's Stillbirth themed issue
Read the full study

 

Why and how was the study carried out?

  • Each year, around 2.6 million babies are stillborn, 15 million are born preterm (<37 weeks of gestation), and 32 million are born small for gestational age (less than tenth percentile for weight, smaller than usually expected for the relevant pregnancy stage).
  • Being born preterm or small for gestational age can increase the chance of long-term health problems.
  • The effect of having a stillbirth, preterm birth, or small-for-gestational-age infant in a previous pregnancy on future pregnancy health has not been summarised.
  • We identified 3399 studies of outcomes of previous pregnancies, and 17 were summarised by our study.

 

What were the main findings?

  • The outcome of the previous pregnancy influenced the risk of poor outcomes in the next pregnancy.
  • Babies born to mothers who had a previous preterm birth or small-for-gestational-age birth were more likely to be stillborn.
  • The smaller and the more preterm the previous baby, the higher the risk of stillbirth in the following pregnancy. The risk of stillbirth in the following pregnancy was doubled if the previous baby was born both preterm and small for gestational age.
  • Babies born to mothers who had a previous stillbirth were more likely to be preterm or small for gestational age.

 

What are the limitations of the work?

  • We included a small number of studies, as there are not enough studies in this area (adverse birth outcomes followed by adverse cross outcomes in the next pregnancy).
  • We found very few studies that compared the risk of small for gestational age after preterm birth or stillbirth.
  • Definitions of stillbirth, preterm birth categories, and small for gestational age differed across studies.
  • We did not know the cause of stillbirth for most studies.

 

What are the implications for patients?

  • Women who have a history of poor pregnancy outcomes are at greater risk of poor outcomes in following pregnancies.
  • Health providers should be aware of this risk when treating patients with a history of poor pregnancy outcomes.

 

 

Reproduced from: Malacova E, Regan A, Nassar N, Raynes-Greenow C, Leonard H, Srinivasjois R, Shand A, Lavin T, Pereira G. Risk of stillbirth, preterm delivery, and fetal growth restriction following exposure in a previous birth: systematic review and meta-analysis. BJOG 2018;125:183–192 https://doi.org/10.1111/1471-0528.14906