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Gestational-age-specific reference ranges for blood pressure in pregnancy: findings from a prospective cohort.

Macdonald-Wallis C, Silverwood RJ, Fraser A, Nelson SM, Tilling K, Lawlor DA, de Stavola BL - J. Hypertens. (2015)

Bottom Line: Stratified reference ranges were higher for women in higher prepregnancy BMI categories, and lower for smokers than for nonsmokers throughout pregnancy.Normal ranges for blood pressure vary with gestation age and by maternal subgroups.Whole population and stratified normograms could be used as a reference to identify abnormal trajectories.

View Article: PubMed Central - PubMed

Affiliation: aMRC Integrative Epidemiology Unit at the University of Bristol bSchool of Social and Community Medicine, University of Bristol, Bristol cCentre for Statistical Methodology dDepartment of Medical Statistics, London School of Hygiene and Tropical Medicine, London eSchool of Medicine, University of Glasgow, Glasgow, UK.

ABSTRACT

Objective: Pregnancy is a period of considerable change in blood pressure, with an early pregnancy decrease followed by a late pregnancy rise. High blood pressure in pregnancy is associated with adverse perinatal outcomes for the mother and offspring. We aimed to define normal ranges of blood pressure across gestation.

Methods: We used repeated antenatal blood pressure measurements [median (interquartile range) 10 (9-11) per woman] for 10,327 women. Multilevel models were used to derive longitudinal reference ranges for SBP and DBP from 12 to 40 weeks gestation for the whole cohort, for women with normal pregnancies (without essential hypertension or preeclampsia who delivered an appropriate-size-for-gestational age infant at term) and for subgroups of normal pregnancies defined by different levels of maternal prepregnancy BMI, smoking and parity.

Results: In normal pregnancies, the mean (95% reference range) SBP and DBP for iparous women at 12 weeks gestation were 112.1 (88.6-135.5) and 65.4 (48.9-81.9) mmHg, and at 37 weeks were 116.0 (92.3-139.7) and 70.0 (52.2-87.9) mmHg, respectively. For every additional 10  mm Hg of blood pressure at 12 weeks, normal ranges were 2-3 mm Hg higher across gestation. Reference ranges for multiparous women were 1-2  mm Hg lower throughout pregnancy. Stratified reference ranges were higher for women in higher prepregnancy BMI categories, and lower for smokers than for nonsmokers throughout pregnancy.

Conclusion: Normal ranges for blood pressure vary with gestation age and by maternal subgroups. Whole population and stratified normograms could be used as a reference to identify abnormal trajectories.

No MeSH data available.


Related in: MedlinePlus

Reference ranges for SBP and DBP between 12 and 40 weeks gestation in the full cohort with complete data (iparous N = 4718; multiparous N = 5609) and in normal pregnancies only (iparous N = 3372; multiparous N = 4132). Centiles are labelled. A normal pregnancy was defined as one in which the woman did not have essential hypertension, preeclampsia, existing or gestational diabetes and delivered an appropriate-for-gestational-age sized infant at term.
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Figure 1: Reference ranges for SBP and DBP between 12 and 40 weeks gestation in the full cohort with complete data (iparous N = 4718; multiparous N = 5609) and in normal pregnancies only (iparous N = 3372; multiparous N = 4132). Centiles are labelled. A normal pregnancy was defined as one in which the woman did not have essential hypertension, preeclampsia, existing or gestational diabetes and delivered an appropriate-for-gestational-age sized infant at term.

Mentions: Figure 1 shows the reference ranges for SBP and DBP between 12 and 40 weeks gestation for all women and for those women who had a normal pregnancy, by parity. The predicted values and 95% reference ranges at 12, 20 and 37 weeks gestation are summarized in Supplementary Table 2. The reference ranges for SBP and DBP decreased until mid-pregnancy in both iparous and multiparous women before rising until the end of pregnancy, although the decrease was more pronounced in multiparous women than in iparous women. The average timing of the nadir in SBP varied, occurring at 17 weeks in iparous women and 18 weeks in multiparous women in the whole cohort and also when restricting to normal pregnancies. The nadir in DBP occurred at around 19 weeks of gestation in iparous women and 20 weeks in multiparous women in the whole cohort and at around 20 weeks for both iparous and multiparous women when restricting to normal pregnancies. The 95% reference range for SBP was approximately 45–50 mmHg wide and for DBP was approximately 30–35 mmHg wide in the whole cohort, both widening slightly towards the end of gestation. Upper reference range limits were generally slightly lower across gestation in normal pregnancies than in the whole cohort but, as ranges were also slightly narrower, the lower reference range limits were similar in the whole cohort and in normal pregnancies.


Gestational-age-specific reference ranges for blood pressure in pregnancy: findings from a prospective cohort.

Macdonald-Wallis C, Silverwood RJ, Fraser A, Nelson SM, Tilling K, Lawlor DA, de Stavola BL - J. Hypertens. (2015)

Reference ranges for SBP and DBP between 12 and 40 weeks gestation in the full cohort with complete data (iparous N = 4718; multiparous N = 5609) and in normal pregnancies only (iparous N = 3372; multiparous N = 4132). Centiles are labelled. A normal pregnancy was defined as one in which the woman did not have essential hypertension, preeclampsia, existing or gestational diabetes and delivered an appropriate-for-gestational-age sized infant at term.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255761&req=5

Figure 1: Reference ranges for SBP and DBP between 12 and 40 weeks gestation in the full cohort with complete data (iparous N = 4718; multiparous N = 5609) and in normal pregnancies only (iparous N = 3372; multiparous N = 4132). Centiles are labelled. A normal pregnancy was defined as one in which the woman did not have essential hypertension, preeclampsia, existing or gestational diabetes and delivered an appropriate-for-gestational-age sized infant at term.
Mentions: Figure 1 shows the reference ranges for SBP and DBP between 12 and 40 weeks gestation for all women and for those women who had a normal pregnancy, by parity. The predicted values and 95% reference ranges at 12, 20 and 37 weeks gestation are summarized in Supplementary Table 2. The reference ranges for SBP and DBP decreased until mid-pregnancy in both iparous and multiparous women before rising until the end of pregnancy, although the decrease was more pronounced in multiparous women than in iparous women. The average timing of the nadir in SBP varied, occurring at 17 weeks in iparous women and 18 weeks in multiparous women in the whole cohort and also when restricting to normal pregnancies. The nadir in DBP occurred at around 19 weeks of gestation in iparous women and 20 weeks in multiparous women in the whole cohort and at around 20 weeks for both iparous and multiparous women when restricting to normal pregnancies. The 95% reference range for SBP was approximately 45–50 mmHg wide and for DBP was approximately 30–35 mmHg wide in the whole cohort, both widening slightly towards the end of gestation. Upper reference range limits were generally slightly lower across gestation in normal pregnancies than in the whole cohort but, as ranges were also slightly narrower, the lower reference range limits were similar in the whole cohort and in normal pregnancies.

Bottom Line: Stratified reference ranges were higher for women in higher prepregnancy BMI categories, and lower for smokers than for nonsmokers throughout pregnancy.Normal ranges for blood pressure vary with gestation age and by maternal subgroups.Whole population and stratified normograms could be used as a reference to identify abnormal trajectories.

View Article: PubMed Central - PubMed

Affiliation: aMRC Integrative Epidemiology Unit at the University of Bristol bSchool of Social and Community Medicine, University of Bristol, Bristol cCentre for Statistical Methodology dDepartment of Medical Statistics, London School of Hygiene and Tropical Medicine, London eSchool of Medicine, University of Glasgow, Glasgow, UK.

ABSTRACT

Objective: Pregnancy is a period of considerable change in blood pressure, with an early pregnancy decrease followed by a late pregnancy rise. High blood pressure in pregnancy is associated with adverse perinatal outcomes for the mother and offspring. We aimed to define normal ranges of blood pressure across gestation.

Methods: We used repeated antenatal blood pressure measurements [median (interquartile range) 10 (9-11) per woman] for 10,327 women. Multilevel models were used to derive longitudinal reference ranges for SBP and DBP from 12 to 40 weeks gestation for the whole cohort, for women with normal pregnancies (without essential hypertension or preeclampsia who delivered an appropriate-size-for-gestational age infant at term) and for subgroups of normal pregnancies defined by different levels of maternal prepregnancy BMI, smoking and parity.

Results: In normal pregnancies, the mean (95% reference range) SBP and DBP for iparous women at 12 weeks gestation were 112.1 (88.6-135.5) and 65.4 (48.9-81.9) mmHg, and at 37 weeks were 116.0 (92.3-139.7) and 70.0 (52.2-87.9) mmHg, respectively. For every additional 10  mm Hg of blood pressure at 12 weeks, normal ranges were 2-3 mm Hg higher across gestation. Reference ranges for multiparous women were 1-2  mm Hg lower throughout pregnancy. Stratified reference ranges were higher for women in higher prepregnancy BMI categories, and lower for smokers than for nonsmokers throughout pregnancy.

Conclusion: Normal ranges for blood pressure vary with gestation age and by maternal subgroups. Whole population and stratified normograms could be used as a reference to identify abnormal trajectories.

No MeSH data available.


Related in: MedlinePlus