Blood pressure in healthy pregnancy and factors associated with no mid-trimester blood pressure drop: a prospective cohort study.
BACKGROUND
The well-known mid-trimester drop in blood pressure (BP) during normal pregnancy was recently questioned.


OBJECTIVE
To describe longitudinal changes in BP during healthy pregnancies and to investigate factors associated with no mid-trimester drop in BP.


METHODS
A prospective cohort with 158 healthy pregnant women was followed up in a public health care center in Rio de Janeiro, Brazil. We used linear mixed-effects models to estimate longitudinal changes in systolic BP (SBP) and diastolic BP (DBP) during pregnancy. Poisson regression models were performed to identify factors associated with no mid-trimester drop in BP.


RESULTS
Significant mid-trimester increase in SBP (5.6 mm Hg; 95% confidence interval (CI) = 4.6-6.7) and DBP (4.4 mm Hg; 95% CI = 3.4-5.3) was observed in 44.3% and 39.9% of the sample, respectively. Women (37.1%) who had not a mid-trimester SBP drop still had a DBP drop. White skin color (incidence ratio (IR): 1.71; 95% CI = 1.22-2.39), family history of hypertension (IR: 1.93; 95% CI = 1.29-2.89), early pregnancy obesity (IR: 2.29; 95% CI = 1.27-4.11), outside temperature variation (IR: 1.45; 95% CI = 1.00-2.10), and gestational weight gain from the first to second trimester (IR: 1.71; 95% CI = 1.01-2.88 and IR: 2.32; 95% CI = 1.39-3.89 for second and third tertiles) were characteristics associated with no mid-trimester drop in SBP. The same characteristics were associated with no mid-trimester drop in DBP, except family history of hypertension and outside temperature variation.


CONCLUSIONS
Some women without a mid-trimester SBP drop still present a DBP drop. The different patterns of mid-trimester change in BP seem to be determined by preexisting and pregnancy-related factors.
Department of Internal Medicine, University Hospital Clementino Fraga Filho, School of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil;
Gil F
GF
Salles
Oxford Clinical Trials Research Unit, Centre for Statistics in Medicine, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK;
Michael M
MM
Schlüssel
Nutritional Epidemiology Observatory, Department of Social and Applied Nutrition, Josué de Castro Institute of Nutrition, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil;
Dayana R
DR
Farias
Nutritional Epidemiology Observatory, Department of Social and Applied Nutrition, Josué de Castro Institute of Nutrition, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil;
Ana Beatriz
AB
Franco-Sena
National School of Public Health, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil;
Fernanda
F
Rebelo
Department of Nutrition and Dietetics, Josué de Castro Institute of Nutrition, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
Elisa M A
EM
Lacerda
Nutritional Epidemiology Observatory, Department of Social and Applied Nutrition, Josué de Castro Institute of Nutrition, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; gilberto.kac@gmail.com.
Gilberto
G
Kac
D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D001795:Blood Pressure Determination; D001938:Brazil / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000503:physiopathology*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology / Q000503:physiopathology*; D011262:Pregnancy Trimester, Second / Q000502:physiology*; D015995:Prevalence; D011446:Prospective Studies; D012016:Reference Values
blood pressure; cohort studies; epidemiology; hypertension; pregnancy.