Cohort Profile: NICHD Fetal Growth Studies–Singletons and Twins

Abstract

Why was the cohort set up? Optimal fetal growth is a foundation for long-term health, whereas abnormal growth affects disease risk across the lifespan. Both fetal growth restriction and overgrowth are associated with increased fetal, infant and child mortality and morbidity, 1,2 as well as being factors in reproductive disorders and later-onset diseases. Population-level data suggest a relationship between diminished birth size and chronic disorders, including hypertension, 3,4 supporting the early origins of health and disease research paradigm. 5 Despite the importance of adequate fetal growth, no US standards for ultrasound-measured fetal growth exist. Existing natality references describe the gestational age distribution of birthweight for all fetuses, including growth-restricted preterm infants and infants of diabetic mothers. 6-8 Existing ultrasound references have generally been constructed from local convenience samples which are not representative of the US population. In contrast, ultrasonographic standards can be purposefully developed to reflect optimal growth by restricting study populations

Vitamin D status during pregnancy and the risk of gestational diabetes mellitus: A longitudinal study in a multiracial cohort

“…We performed a nested case‐control study using the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies‐Singleton cohort (2009‐2013), consisting of 2802 generally healthy multiracial women (2334 non‐obese and 468 obese women) with singleton pregnancies and aged 18 to 40 years at enrolment. All women were enrolled between 8 weeks, 0 days and 13 weeks, 6 days of gestation at 12 clinical centres throughout the United States and were followed up throughout their pregnancies . For participants to be eligible, ultrasound estimates of gestational age at enrolment were required to be consistent (±5‐7 days) with gestational dating, calculated by last menstrual period.…”

“…For participants to be eligible, ultrasound estimates of gestational age at enrolment were required to be consistent (±5‐7 days) with gestational dating, calculated by last menstrual period. Sampling and eligibility criteria are described in detail elsewhere . The study was approved by all participating institutions including NICHD.…”

Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study

“…13 The primary objective of the NICHD Study was also to create optimal fetal growth standards. 23 Unlike the two international studies, the NICHD Study was designed to assess whether racial/ethnic fetal growth standards were needed, in recognition of the fact that because fetal size is commonly estimated from dimensions, particularly post-cranial dimensions (i.e., abdominal circumference [AC] and femur length [FL]), where there are known differences in children and adults of differing racial/ethnic groups, separate standards might be necessary to capture optimal growth and more precisely estimate fetal weight. 24, 25 Highly statistically significant racial/ethnic differences in fetal growth were found, and by order of detection were: humerus and femur lengths (beginning as early as 10 weeks), abdominal circumference (16 weeks), head circumference (21 weeks), and biparietal diameter (27 weeks) with racial/ethnic differences continuing throughout gestation, so racial/ethnic-specific curves were derived.…”

Associations between estimated foetal weight discordance and clinical characteristics within dichorionic twins: The NICHD Fetal Growth Studies

“…In the NICHD Fetal Growth Studies—Dichorionic Twins study cohort, from February 2012‐January 2013, 171 women with dichorionic twin pregnancies, dated between 8 weeks 0 days and 13 weeks 6 days of gestation by last menstrual period‐based gestational age matching first‐trimester ultrasound, were recruited from 8 US sites. Dichorionicity was verified by the existence of two gestational sacs with a thick intervening membrane or with twin peak or lambda sign at an initial study ultrasound conducted at 11 weeks 0 days through 13 weeks 6 days.…”

“…Information related to study procedures and methodology, data collected, and quality control/assurance procedures, including sonographer training and credentialing and random re‐measurement, has been reported elsewhere . Foetal biometrics obtained in ultrasounds underwent extensive data cleaning and quality control and assurance analysis as described for singleton pregnancies, with high correlation/low variation between site sonographer and expert reviewer measurements indicating excellent reliability.…”