Stillbirths: Contribution of preterm birth and size‐for‐gestational age for 125.4 million total births from nationwide records in 13 countries, 2000–2020
Yemisrach B. Okwaraji, Lorena Suárez‐Idueta, Eric O. Ohuma, Ellen Bradley, Judith Yargawa, Veronica Pingray, Gabriela Cormick, Adrienne Gordon, Vicki Flenady, Erzsébet Horváth‐Puhó, Henrik Toft Sørensen, Luule Sakkeus, Liili Abuladze, Mohammed Heidarzadeh, Narjes Khalili, Khalid A. Yunis, Ayah Al Bizri, Shamala D. Karalasingam, Ravichandran Jeganathan, Arturo Barranco, Aimée E. van Dijk, Lisa Broeders, Fawzya Alyafei, Mai AlQubaisi, Neda Razaz, Jonas Söderling, Lucy K. Smith, Ruth J. Matthews, Rachael Wood, Kirsten Monteath, Isabel Pereyra, Gabriella Pravia, Sarka Lisonkova, Qi Wen, Joy E. Lawn, Hannah Blencowe,- Obstetrics and Gynecology
Abstract
Objective
To examine the contribution of preterm birth and size‐for‐gestational age in stillbirths using six ‘newborn types’.
Design
Population‐based multi‐country analyses.
Setting
Births collected through routine data systems in 13 countries.
Sample
125 419 255 total births from 22+0 to 44+6 weeks’ gestation identified from 2000 to 2020.
Methods
We included 635 107 stillbirths from 22+0 weeks’ gestation from 13 countries. We classified all births, including stillbirths, into six ‘newborn types’ based on gestational age information (preterm, PT, <37+0 weeks versus term, T, ≥37+0 weeks) and size‐for‐gestational age defined as small (SGA, <10th centile), appropriate (AGA, 10th–90th centiles) or large (LGA, >90th centile) for gestational age, according to the international newborn size for gestational age and sex INTERGROWTH‐21st standards.
Main outcome measures
Distribution of stillbirths, stillbirth rates and rate ratios according to six newborn types.
Results
635 107 (0.5%) of the 125 419 255 total births resulted in stillbirth after 22+0 weeks. Most stillbirths (74.3%) were preterm. Around 21.2% were SGA types (PT + SGA [16.2%], PT + AGA [48.3%], T + SGA [5.0%]) and 14.1% were LGA types (PT + LGA [9.9%], T + LGA [4.2%]). The median rate ratio (RR) for stillbirth was highest in PT + SGA babies (RR 81.1, interquartile range [IQR], 68.8–118.8) followed by PT + AGA (RR 25.0, IQR, 20.0–34.3), PT + LGA (RR 25.9, IQR, 13.8–28.7) and T + SGA (RR 5.6, IQR, 5.1–6.0) compared with T + AGA. Stillbirth rate ratios were similar for T + LGA versus T + AGA (RR 0.7, IQR, 0.7–1.1). At the population level, 25% of stillbirths were attributable to small‐for‐gestational‐age.
Conclusions
In these high‐quality data from high/middle income countries, almost three‐quarters of stillbirths were born preterm and a fifth small‐for‐gestational age, with the highest stillbirth rates associated with the coexistence of preterm and SGA. Further analyses are needed to better understand patterns of gestation‐specific risk in these populations, as well as patterns in lower‐income contexts, especially those with higher rates of intrapartum stillbirth and SGA.