Miscarriage, stillbirth and neonatal mortality in the extreme preterm birth window of gestation in a limited-resource setting on the Thailand-Myanmar border: A population cohort study

Introduction
The WHO definition of stillbirth uses 28 weeks’ gestation as the cut-point, but also defines extreme preterm birth as 24 to <28 weeks’ gestation. This presents a problem with the gestational limit of miscarriage, and hence reporting of stillbirth, preterm birth and neonatal death. The objective of this study is to provide a synopsis of the outcome of a population cohort of pregnancies on the Thailand-Myanmar border between 24 to <28 weeks’ gestation.
Methods
Records from the Shoklo Malaria Research Unit Antenatal Clinic were reviewed for pregnancy outcomes in the gestational window of 24 to <28 weeks, and each record, including ultrasounds reports, were reviewed to clarify the pregnancy outcome. Pregnancies where there was evidence of fetal demise prior to 24 weeks were classified as miscarriage; those viable at 24 weeks’ gestation and born before 28 weeks were coded as births, and further subdivided into live- and stillbirth.
Results
Between 1995 and 2015, in a cohort of 49,931 women, 0.6% (318) of outcomes occurred from 24 to <28 weeks’ gestation, and 35.8% (114) were miscarriages, with confirmatory ultrasound of fetal demise in 45.4% (49/108). Of pregnancies not ending in miscarriage, 37.7% (77/204) were stillborn and of those born alive, neonatal mortality was 98.3% (115/117). One infant survived past the first year of life. Congenital abnormality rate was 12.0% (23/191). Ultrasound was associated with a greater proportion of pregnancy outcome being coded as delivery.
Conclusion
In this limited-resource setting, pregnancy outcome from 24 to <28 weeks’ gestation included: 0.6% of all outcomes, of which one-third were miscarriages, one-third of births were stillborn and mortality of livebirths approached 100%. In the scale-up to preventable newborns deaths, at least initially, greater benefits will be obtained by focusing on the greater number of viable newborns with a gestation of 28 weeks or more.
KEYWORDS: extreme preterm birth, limited-resource, low-income, marginalized, miscarriage, neonatal death, stillbirth, ultrasound