G4. Does maternal obesity have an adverse effect on haemodynamics?

BACKGROUND: The increase in the prevalence of and the adverse risks to both mother and foetus associated with maternal obesity is a global concern. The adverse cardiovascular risk associated with obesity is well-known, however, there is a paucity of data assessing central haemodynamics in class 3 (morbid) obesity (BMI440 kg/m(2)) during pregnancy.

OBJECTIVE: To compare the haemodynamic profile in women with class 3 maternal obesity against those with a normal BMI (20-30 kg/m(2)), using ultrasound-based, non-invasive haemodynamic monitoring.

METHODS: A prospective, case-control study of 23 women with class 3 maternal obesity and 327 controls, matched for maternal and gestational age. Women who developed hypertensive disorders of pregnancy (HDP) were not included. Maternal haemodynamics were investigated using USCOM 1A®.

RESULTS: Women with class 3 obesity had raised mean arterial pressure (91 versus 85 mmHg, p < 0.01) and increased heart rate (92 versus 83 bpm, p < 0.05) compared to controls. We found no difference in stroke volume (77 versus 82 mL), cardiac output (7.04 versus 6.75 L/min) or total peripheral resistance (TPR) (1106 versus 1052 dyn·s·cm(5)). When haemodynamic indices were corrected for body surface area, women with class 3 obesity exhibited a lower stroke volume index 33 versus 46 mL (p < 0.01), lower cardiac index 3.01 versus 3.70 L/min/m(2) (p < 0.01) and higher TPR index 2567 versus 1915 dyn·s·cm(5)/m(2) (p < 0.01).

CONCLUSIONS: Morbid obesity in pregnancy is associated with an adverse haemodynamic profile compared to women of normal weight and independent of HDP. The aberrant haemodynamics observed in obesity are consistent with findings in outside pregnancy and the predisposition of obese women to HDP. Given the differences in anthropometric parameters observed in the pregnant population, haemodynamic indices should be corrected for body surface area to allow appropriate interpretation.