Optimizing GWG in Obese Pregnant Women: A Nationwide Real-World Study Using the U.S. Natality Cohort

NCT07796815 | Completed

• 1 other identifier: 20260826
• Study Type: observational
• Target: 1,600,000
• Locations: 1 country
• Sites: 1

Brief Summary

The goal of this observational study is to find out which amount of weight gain during pregnancy is safest for women with obesity and their babies. Current guidelines recommend the same weight gain target (5 to 9 kg) for all women with obesity. However, obesity has different levels of severity. The same target may not work well for everyone. Researchers will look at health data from about 10 million U.S. birth records between 2023 and 2025. They will focus on women aged 18 to 45 who had a single baby at full term (37 to 41 weeks) and had obesity before pregnancy. All women in this study started prenatal care in their first 3 months of pregnancy. The study divides total pregnancy weight gain into 8 different ranges. Then, it checks for maternal and newborn health problems. Serious problems include stays in the intensive care unit (ICU) or blood transfusions. Moderate problems include high blood pressure during pregnancy, diabetes, or babies born too large or too small. By comparing weight gain ranges across three obesity classes, this study aims to find specific target weight ranges for each class. The ultimate goal is to lower the risk of both severe and moderate pregnancy complications for mothers and their newborns

Conditions

Pregnancy in Obesity; Gestational Weight Gain

Keywords

Pregnancy in Obesity; Gestational Weight Gain; Pregnancy Complications; Body Mass Index

Outcome Measures

Primary Outcomes (2)

• Maternal Composite Adverse Outcome (M1_equal)

  Occurrence of any of the following severe (Tier 1) or moderate (Tier 2) maternal events: ICU admission, blood transfusion, eclampsia, gestational hypertension, gestational diabetes mellitus, primary cesarean delivery, or perineal laceration.

  At delivery

• Neonatal Composite Adverse Outcome (M2_equal)

  Occurrence of any of the following severe (Tier 1) or moderate (Tier 2) neonatal events: NICU admission, prolonged assisted ventilation (\>6 hours), neonatal seizures, small for gestational age (\<10th percentile), large for gestational age (\>90th percentile), immediate assisted ventilation, or 5-minute Apgar score \<7.

  At delivery

Secondary Outcomes (2)

• Graded Maternal Adverse Outcome (M1_grade)

  At delivery

• Graded Neonatal Adverse Outcome (M2_grade)

  At delivery

Study Arms (1)

Obese Pregnant Women in the U.S. Natality Cohort (2023-2025)

All participants are pregnant individuals aged 18-45 years with pre-pregnancy obesity (BMI ≥ 30.0 kg/m²), singleton live-born term infants (37-41 weeks), and first-trimester prenatal care initiation, identified from the U.S. National Vital Statistics System (NVSS) natality files from 2022 to 2024.

Behavioral: Gestational Weight Gain

Interventions

Gestational Weight Gain BEHAVIORAL

Total gestational weight gain, calculated as the difference between maternal weight at delivery and pre-pregnancy weight. Categorized into eight prespecified clinical intervals ranging from weight loss (\<0 kg) to excessive gain (≥16.0 kg), with the 5.0-9.0 kg interval (2009 IOM guideline for obese individuals) serving as the reference category.

Obese Pregnant Women in the U.S. Natality Cohort (2023-2025)

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64)
• Sampling Method: Non-Probability Sample

Study Population

The study population comprises all individuals with a documented live birth in the United States between January 1, 2023, and December 31, 2025, whose records are captured in the National Vital Statistics System (NVSS) natality files. The NVSS is a nationwide, population-based registry maintained by the National Center for Health Statistics (NCHS), covering nearly 100% of U.S. births. All data are de-identified and publicly available through the CDC's website. Participants are drawn from all 50 states and the District of Columbia, representing diverse geographic regions, racial/ethnic groups, and socioeconomic backgrounds. This secondary analysis uses only existing administrative and health records reported on birth certificates; no direct contact with participants occurs.

You may qualify if:

• Nulliparous or multiparous individuals aged 18 to 45 years at delivery. Singleton, live-born, term pregnancy (37 to 41 completed weeks of gestation). Pre-pregnancy obesity, defined as body mass index (BMI) ≥ 30.0 kg/m². Initiation of prenatal care during the first trimester (months 1-3 of pregnancy).

You may not qualify if:

• Missing data on pre-pregnancy weight, delivery weight, or birth weight. Implausible gestational weight gain (GWG) values: \< -10 kg or \> 50 kg. Unknown mode of delivery or documented prior cesarean section.

Sponsors & Collaborators

• Shanghai First Maternal and Infant Health Hospital affiliated to Tongji University Medical School: lead

Study Sites (1)

National Vital Statistics System (NVSS) - United States

Hyattsville, Maryland, 20782, United States

Location

Related Publications (5)

• Say L, Souza JP, Pattinson RC; WHO working group on Maternal Mortality and Morbidity classifications. Maternal near miss--towards a standard tool for monitoring quality of maternal health care. Best Pract Res Clin Obstet Gynaecol. 2009 Jun;23(3):287-96. doi: 10.1016/j.bpobgyn.2009.01.007. Epub 2009 Mar 19.

  PMID: 19303368 BACKGROUND

• American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine; Kilpatrick SK, Ecker JL. Severe maternal morbidity: screening and review. Am J Obstet Gynecol. 2016 Sep;215(3):B17-22. doi: 10.1016/j.ajog.2016.07.050. Epub 2016 Aug 22.

  PMID: 27560600 BACKGROUND

• Langan SM, Schmidt SA, Wing K, Ehrenstein V, Nicholls SG, Filion KB, Klungel O, Petersen I, Sorensen HT, Dixon WG, Guttmann A, Harron K, Hemkens LG, Moher D, Schneeweiss S, Smeeth L, Sturkenboom M, von Elm E, Wang SV, Benchimol EI. The reporting of studies conducted using observational routinely collected health data statement for pharmacoepidemiology (RECORD-PE). BMJ. 2018 Nov 14;363:k3532. doi: 10.1136/bmj.k3532.

  PMID: 30429167 BACKGROUND

• von Elm E, Altman DG, Egger M, Pocock SJ, Gotzsche PC, Vandenbroucke JP; STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Ann Intern Med. 2007 Oct 16;147(8):573-7. doi: 10.7326/0003-4819-147-8-200710160-00010.

  PMID: 17938396 BACKGROUND

• Aris IM, Kleinman KP, Belfort MB, Kaimal A, Oken E. A 2017 US Reference for Singleton Birth Weight Percentiles Using Obstetric Estimates of Gestation. Pediatrics. 2019 Jul;144(1):e20190076. doi: 10.1542/peds.2019-0076. Epub 2019 Jun 14.

  PMID: 31201230 BACKGROUND

MeSH Terms

Conditions

Pregnancy in Obesity; Gestational Weight Gain; Pregnancy Complications

Condition Hierarchy (Ancestors)

Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Obesity; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Weight Gain; Body Weight Changes

Study Officials

• Hao Ying, MD & PhD

  Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University, Shanghai, P.R. China

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: August 27, 2026
• First Posted: September 1, 2026
• Study Start: January 1, 2023
• Primary Completion: December 31, 2025
• Study Completion: December 31, 2025
• Last Updated: September 1, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)