The association between gestational body mass index change, cesarean section, and other pregnancy outcomes: Research

Kirsten I Black1,2, Owen Streeter2, Arianne Sweeting1,2

  • 1Reproduction and Perinatal Centre, Faculty of Medicine and Health, University of Sydney, Sydney, Australia.

Methodsx
|November 24, 2025
PubMed

Increasingly the value of gestational weight gain (GWG) as a useful measure to predict obstetric outcomes including cesarean section is being questioned. We will undertake a retrospective cohort study of recorded births in 2023 from 24 to 42 weeks' gestation for women aged from 16 to 49 years in the United States. Using multivariable Robust Poisson Regression, maternal body mass index (BMI) and BMI gain will be modelled on the primary outcome of cesarean delivery. The primary analysis will be restricted to nulliparous women if there is interaction between parity and BMI or BMI gain. A sample of 716,392 births will be required to show approximately a one percentage point increase in cesarean section for each BMI classification compared with normal BMI (18.5 to <25) or per unit gain in maternal BMI. We hypothesize that the risk of cesarean section will increase with an increase in the BMI category and that BMI at birth may be a more relevant predictor of cesarean section than pre-pregnancy BMI. This question is important to answer given recent evidence casting doubt on the association between excessive GWG, which has been the focus of most interventions (with modest impact at best), and adverse pregnancy outcomes.

Related Concept Videos

Pathophysiology of Diabetes01:20

Pathophysiology of Diabetes

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycemia. The four categories of diabetes are type 1 diabetes, type 2 diabetes, other specific types of diabetes, and gestational diabetes.
Type 1 diabetes is characterized by autoimmune-mediated destruction of pancreatic β cells, with environmental factors potentially triggering this process in genetically susceptible individuals. Despite many not having a family history, certain genes increase susceptibility,...
3.1K
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches01:23

Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches

Biopharmaceutical studies constitute a vital field aiming to enhance drug delivery methods and refine therapeutic approaches, drawing upon diverse interdisciplinary knowledge. In research methodologies, the choice between controlled and non-controlled studies significantly influences the study's reliability and accuracy.
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast,...
387
Diabetes Mellitus: Type 2 and Gestational01:22

Diabetes Mellitus: Type 2 and Gestational

Type 2 diabetes, characterized by insulin resistance, arises when the insulin receptors on cells lose responsiveness to insulin, diminishing the cell's capacity to take up glucose, resulting in elevated blood glucose levels. To receive a diagnosis of Type 2 diabetes, a series of blood glucose tests are necessary to assess whether the blood glucose falls within normal parameters. If the result is out of the normal range, a patient may be diagnosed as prediabetic or diabetic, depending on the...
4.3K
Regression Toward the Mean01:52

Regression Toward the Mean

Regression toward the mean (“RTM”) is a phenomenon in which extremely high or low values—for example, and individual’s blood pressure at a particular moment—appear closer to a group’s average upon remeasuring. Although this statistical peculiarity is the result of random error and chance, it has been problematic across various medical, scientific, financial and psychological applications. In particular, RTM, if not taken into account, can interfere when...
6.8K