Haemorheological adaptation during pregnancy in a Latin American population

Objective: To investigate haemorheological changes during pregnancy in a La tin American population and compare to previously published data from Cauca sian populations. Design: Cross-sectional study. Population: 75 pregnant wo men at 10-36 wk of gestation and 17 non-pregnant female controls in Lima, P eru. All the women and their ancestors for three generations were born and lived at sea level. Methods. Viscosity, haematocrit and plasma fibrinogen, albumin and total protein concentrations were determined in blood samples o btained after an overnight period of fasting. Results: At 10 wk of gestatio n, total protein concentration and plasma viscosity were above non-pregnant levels by about 15% and subsequently decreased linearly with gestation. Fi brinogen concentration was increased in the first trimester; it then decrea sed to a nadir at about 20 wk and subsequently increased. Albumin concentra tion decreased linearly with gestation. Haematocrit decreased from pre-preg nancy levels at 10 wk to a nadir at about 26 wk. Blood viscosity increased in the first trimester and then decreased with gestation to a nadir at abou t 26 wk. Conclusion: In the first trimester of pregnancy blood and plasma v iscosity are increased and they subsequently fall with advancing gestation. Plasma viscosity reflects the changes in total protein concentration, and blood viscosity is dependent on the interplay of changes in plasma viscosit y and haematocrit.