Abstract：
OBJECTIVE: To compare stillbirth rates and risks for small for gestational age (SGA), large for gestational age (LGA) and appropriate for gestational age (AGA) pregnancies at 24-44 completed weeks of gestation using a birth-based and fetuses-at-risk approachs.
METHODS: Population-based, multi-country study.
METHODS: National data systems in 15 high- and middle-income countries.
METHODS: Live births and stillbirths.
METHODS: A total of 151 country-years of data, including 126 543 070 births across 15 countries from 2000 to 2020, were compiled. Births were categorised into SGA, AGA and LGA using INTERGROWTH-21st standards. Gestation-specific stillbirth rates, with total births as the denominator, and gestation-specific stillbirth risks, with fetuses still in utero as the denominator, were calculated from 24 to 44 weeks of gestation.
METHODS: Gestation-specific stillbirth rates and risks according to size at birth.
RESULTS: The overall stillbirth rate was 4.22 per 1000 total births (95% CI 4.22-4.23) across all gestations. Applying the birth-based approach, the stillbirth rates were highest at 24 weeks of gestation, with 621.6 per 1000 total births (95% CI 620.9-622.2) for SGA pregnancies, 298.4 per 1000 total births (95% CI 298.1-298.7) for AGA pregnancies and 338.5 per 1000 total births (95% CI 337.9-339.0) for LGA pregnancies. Applying the fetuses-at-risk approach, the gestation-specific stillbirth risk was highest for SGA pregnancies (1.3-1.4 per 1000 fetuses at risk) prior to 29 weeks of gestation. The risk remained stable between 30 and 34 weeks of gestation, and then increased gradually from 35 weeks of gestation to the highest rate of 8.4 per 1000 fetuses at risk (95% CI 8.3-8.4) at ≥42 weeks of gestation. The stillbirth risk ratio (RR) was consistently high for SGA compared with AGA pregnancies, with the highest RR observed at ≥42 weeks of gestation (RR 9.2, 95% CI 15.2-13.2), and with the lowest RR observed at 24 weeks of gestation (RR 3.1, 95% CI 1.9-4.3). The stillbirth RR was also consistently high for SGA compared with AGA pregnancies across all countries, with national variability ranging from RR 0.70 (95% CI 0.43-0.97) in Mexico to RR 8.6 (95% CI 8.1-9.1) in Uruguay. No increased risk for LGA pregnancies was observed.
CONCLUSIONS: Small for gestational age (SGA) was strongly associated with stillbirth risk in this study based on high-quality data from high- and middle-income countries. The highest RRs were seen in preterm gestations, with two-thirds of the stillbirths born as preterm births. To advance our understanding of stillbirth, further analyses should be conducted using high-quality data sets from low-income settings, particularly those with relatively high rates of SGA.
METHODS: Population-based, multi-country study.
METHODS: National data systems in 15 high- and middle-income countries.
METHODS: Live births and stillbirths.
METHODS: A total of 151 country-years of data, including 126 543 070 births across 15 countries from 2000 to 2020, were compiled. Births were categorised into SGA, AGA and LGA using INTERGROWTH-21st standards. Gestation-specific stillbirth rates, with total births as the denominator, and gestation-specific stillbirth risks, with fetuses still in utero as the denominator, were calculated from 24 to 44 weeks of gestation.
METHODS: Gestation-specific stillbirth rates and risks according to size at birth.
RESULTS: The overall stillbirth rate was 4.22 per 1000 total births (95% CI 4.22-4.23) across all gestations. Applying the birth-based approach, the stillbirth rates were highest at 24 weeks of gestation, with 621.6 per 1000 total births (95% CI 620.9-622.2) for SGA pregnancies, 298.4 per 1000 total births (95% CI 298.1-298.7) for AGA pregnancies and 338.5 per 1000 total births (95% CI 337.9-339.0) for LGA pregnancies. Applying the fetuses-at-risk approach, the gestation-specific stillbirth risk was highest for SGA pregnancies (1.3-1.4 per 1000 fetuses at risk) prior to 29 weeks of gestation. The risk remained stable between 30 and 34 weeks of gestation, and then increased gradually from 35 weeks of gestation to the highest rate of 8.4 per 1000 fetuses at risk (95% CI 8.3-8.4) at ≥42 weeks of gestation. The stillbirth risk ratio (RR) was consistently high for SGA compared with AGA pregnancies, with the highest RR observed at ≥42 weeks of gestation (RR 9.2, 95% CI 15.2-13.2), and with the lowest RR observed at 24 weeks of gestation (RR 3.1, 95% CI 1.9-4.3). The stillbirth RR was also consistently high for SGA compared with AGA pregnancies across all countries, with national variability ranging from RR 0.70 (95% CI 0.43-0.97) in Mexico to RR 8.6 (95% CI 8.1-9.1) in Uruguay. No increased risk for LGA pregnancies was observed.
CONCLUSIONS: Small for gestational age (SGA) was strongly associated with stillbirth risk in this study based on high-quality data from high- and middle-income countries. The highest RRs were seen in preterm gestations, with two-thirds of the stillbirths born as preterm births. To advance our understanding of stillbirth, further analyses should be conducted using high-quality data sets from low-income settings, particularly those with relatively high rates of SGA.
摘要：
目的：比较小于胎龄（SGA）的死胎率和风险，使用基于出生和胎儿风险的方法，在24-44周时进行胎龄大（LGA）和适合胎龄（AGA）妊娠。
方法：以人口为基础，多国研究。
方法：15个高收入和中等收入国家的国家数据系统。
方法：活产和死产。
方法：总共151个国家/地区年的数据，编制了2000年至2020年15个国家的126543070名新生儿。出生被归类为SGA，AGA和LGA使用INTERGROWTH-21标准。妊娠特异性死胎率，以出生总数为分母，和妊娠特定的死产风险，以胎儿仍在子宫内作为分母，计算从24到44周的妊娠。
方法：根据出生时的大小，妊娠特异性死胎率和风险。
结果：所有妊娠的总死胎率为4.22/1000总分娩（95％CI4.22-4.23）。应用基于出生的方法，妊娠24周时死胎率最高,SGA妊娠的总出生人数为621.6/1000（95％CI620.9-622.2），AGA妊娠为每1000名总出生婴儿298.4（95％CI298.1-298.7），LGA妊娠为每1000名总出生婴儿338.5（95％CI337.9-339.0）。应用胎儿风险方法，在妊娠29周前,SGA妊娠的特定死产风险最高(每1000个有风险的胎儿中有1.3~1.4个).妊娠30至34周的风险保持稳定，然后从妊娠35周逐渐增加到妊娠≥42周时每1000个有风险的胎儿中8.4个的最高比率(95%CI8.3-8.4)。与AGA妊娠相比，SGA的死胎风险比（RR）始终较高，在妊娠≥42周时观察到最高RR（RR9.2，95%CI15.2-13.2），在妊娠24周时观察到的RR最低（RR3.1，95%CI1.9-4.3）。与所有国家的AGA妊娠相比，SGA的死胎RR也一直很高，墨西哥的国家差异从RR0.70(95%CI0.43-0.97)到乌拉圭的RR8.6(95%CI8.1-9.1)。未观察到LGA妊娠风险增加。
结论：根据高收入和中等收入国家的高质量数据，本研究中小于胎龄（SGA）与死产风险密切相关。最高的RRs见于早产妊娠,三分之二的死胎是早产。为了提高我们对死产的认识，应使用来自低收入环境的高质量数据集进行进一步分析，特别是那些SGA率相对较高的人。
方法：以人口为基础，多国研究。
方法：15个高收入和中等收入国家的国家数据系统。
方法：活产和死产。
方法：总共151个国家/地区年的数据，编制了2000年至2020年15个国家的126543070名新生儿。出生被归类为SGA，AGA和LGA使用INTERGROWTH-21标准。妊娠特异性死胎率，以出生总数为分母，和妊娠特定的死产风险，以胎儿仍在子宫内作为分母，计算从24到44周的妊娠。
方法：根据出生时的大小，妊娠特异性死胎率和风险。
结果：所有妊娠的总死胎率为4.22/1000总分娩（95％CI4.22-4.23）。应用基于出生的方法，妊娠24周时死胎率最高,SGA妊娠的总出生人数为621.6/1000（95％CI620.9-622.2），AGA妊娠为每1000名总出生婴儿298.4（95％CI298.1-298.7），LGA妊娠为每1000名总出生婴儿338.5（95％CI337.9-339.0）。应用胎儿风险方法，在妊娠29周前,SGA妊娠的特定死产风险最高(每1000个有风险的胎儿中有1.3~1.4个).妊娠30至34周的风险保持稳定，然后从妊娠35周逐渐增加到妊娠≥42周时每1000个有风险的胎儿中8.4个的最高比率(95%CI8.3-8.4)。与AGA妊娠相比，SGA的死胎风险比（RR）始终较高，在妊娠≥42周时观察到最高RR（RR9.2，95%CI15.2-13.2），在妊娠24周时观察到的RR最低（RR3.1，95%CI1.9-4.3）。与所有国家的AGA妊娠相比，SGA的死胎RR也一直很高，墨西哥的国家差异从RR0.70(95%CI0.43-0.97)到乌拉圭的RR8.6(95%CI8.1-9.1)。未观察到LGA妊娠风险增加。
结论：根据高收入和中等收入国家的高质量数据，本研究中小于胎龄（SGA）与死产风险密切相关。最高的RRs见于早产妊娠,三分之二的死胎是早产。为了提高我们对死产的认识，应使用来自低收入环境的高质量数据集进行进一步分析，特别是那些SGA率相对较高的人。
