Table 1.
Summary of methods to measure body composition changes in pregnancy
| Method | Participant complexity |
Technical complexity |
Source of Error | Compartment model |
Regional distribution | Suitable in field settings |
|---|---|---|---|---|---|---|
| Anthropometry—skinfold thickness | Simple | Simple | Measurement error—requires technician expertise. Over the course of pregnancy, changes in (1) compressibility of skinfold thickness, edema and (3) ability to measure certain regions Equations to estimate total body fat available for only certain gestational ages | 2 | Yes | Y |
| Total body water (TBW) | Simple | Specialized instruments | Hydration of fat-free mass. Unable to disentangle the maternal–fetal unit | 2/Multiplea | No | Y |
| Underwater weighing | Complex | Specialized instruments | Unable to disentangle the maternal–fetal unit | 2/Multiplea | No | N |
| Air displacement plethysmography (ADP/BodPod) | Complex | Specialized instruments | Unable to disentangle the maternal–fetal unit | 2/Multiplea | No | N |
| Magnetic resonance imaging (MRI) | Simple | Specialized instruments | Methods have not been developed specifically for pregnancy; therefore, the source of error is not fully understood | 2 | Yes | N |
| Bioelectrical impedance analysis (BIA) | Simple | Specialized, Portable Equipment Depending on model | Has not been validated against reference methods in pregnancy. Unable to disentangle the maternal–fetal unit | 2 | Yes, but not validated | Y |
| Dual energy X-ray absorptiometry (DEXA) | Simple—for use in prenatal and postnatal | Specialized instrument | Not suitable during pregnancy due to radiation exposure. Bone mineral content estimates used for four-compartment models. Fat and fat-free mass estimates prone to error due to changes in the composition of lean tissue that may persist into the postpartum period | 2/Multiplea | Yes, but not validated | N |
| Ultrasound | Simple | Specialized instrument, available in most hospital settings | Estimates regional adiposity, not total body composition. Has not been validated against reference methods in pregnancy | Yes, but not validated | N |
a
These methods are used for multi-component models in combination with other body composition measurements and body mass.