Table 2.

Body composition assessment methods in pregnancy

Method	Measures	Strengths	Weaknesses
Skinfold thickness	Estimate of FM Use of skinfold thickness measurements themselves rather than estimates of FM and FFM are often preferred	Simple, inexpensive	Equations to estimate total BF, taking into account the change in hydration of the FFM, only available for certain gestational ages
Bioelectrical impedance analysis	TBW, FM, FFM, ECW, ICW	Simple, inexpensive	Equations to estimate total BF only available for certain gestational ages; unable to disentangle the maternal–fetal unit
Underwater weighing	Body volume (estimate FM and FFM)	Accurate	Method requiring complex equipment. Unable to disentangle the maternal–fetal unit. Results are influenced by changes in hydration of FFM during pregnancy
Air displacement plethysmography (ADP/BOD POD)	Body volume (estimate FM and FFM)	Accurate	Expensive and requiring complex equipment. Unable to disentangle the maternal–fetal unit. Result influenced by changes in hydration of FFM during pregnancy
Isotopic dilution	TBW (estimate FFM)	Accurate	Require frequent urine collection. For research only. It is expensive and requires complex equipment and experienced technicians
Whole-body potassium counting	BCM, FFM	Accurate	It is expensive and requires complex equipment; less accurate during pregnancy due to variation in postassi content in the FFM
Magnetic resonance imaging	FM, FFM, Ectopic FAT, FAT distribution	Accurate	For research only. It is expensive and requires complex equipment and experienced technicians
Dual energy X-ray absorptiometry	FM, FFM, Bone density	Contraindicated during pregnancy due to the radiation exposure

BF: body fat; TBW total body water; FM fat mass; FFM fat-free mass; ECW extracellular water; ICW intracellular water; BCM body cell mass