Modelling the association of blood pressure during pregnancy with gestational age and body mass index

Doing it all: Effects of Family Responsibilities and Marital Relationship Quality on Mothers' Ambulatory Blood Pressure

BACKGROUND

The shared provider responsibility between married couples does not translate to equally shared division of childcare (CC) and household labor. While some marriages contain highly positive aspects, marriages may also simultaneously contain both positive and negative aspects. The negativity in these relationships can negate the positivity and could potentially lead to the detriment of mothers' health.

PURPOSE

We examined mothers' ambulatory blood pressure (ABP) associated with their marital relationship quality and perceived equity with her spouse on CC and household tasks.

METHODS

We investigate these associations using a mixed multilevel model analysis on a sample of 224 mothers in heterosexual marriages, all of whom had children under the age of 18 years currently living in the home.

RESULTS

Mothers' perception of equity in the division of CC responsibilities contributed to lower ABP. Additionally, mothers in supportive marital relationships (low negativity and high positivity) had lower ABP than those in ambivalent relationships (both high negativity and positivity). There was a crossover interaction such that the effect of relationship quality on ABP was moderated by the perception of equity in the division of CC. For mothers who report doing all the CC, they had lower ABP if they had a supportive marital relationship compared with mothers in ambivalent relationships. Whereas mothers who report more equity in CC and have a supportive relationship have higher ABP compared with mothers in ambivalent relationships.

CONCLUSIONS

This study has implications related to dynamics within marital relationships. These results demonstrate important relational influences on mothers' ABP.

A prospective study of arsenic and manganese exposures and maternal blood pressure during gestation

BACKGROUND

Pregnancy is a sensitive time for maternal cardiovascular functioning and exposures to arsenic or manganese may adversely affect blood pressure (BP).

OBJECTIVES

This study examined the associations between arsenic and manganese exposures and maternal BP measured during pregnancy. Effect modification by pre-pregnancy body mass index (BMI) was evaluated.

METHODS

Pregnant women (N = 1522) were recruited for a prospective cohort study in Bangladesh (2008-2011). Exposure to arsenic and manganese was measured in drinking water at <16 weeks gestation and toenails at one-month postpartum. Systolic and diastolic BP were measured monthly. Linear mixed models estimated mean BP and differences in mean BP over gestation for arsenic or manganese exposures and adjusted for covariates.

RESULTS

Arsenic levels had an increasing dose-response association with maternal BP after 25 weeks gestation. Effect modification was observed for BMI. Participants with lower BMI (<23 kg/m²) exposed to 50 μg/L arsenic had 2.83 mmHg (95% CI:1.74-3.92) greater mean systolic and 1.96 mmHg (95% CI: 1.02-2.91 mmHg) diastolic BP compared to those exposed to ≤ 1 μg/L arsenic at 40 weeks gestation. Participants with higher BMI (≥23 kg/m²) showed a greater mean systolic BP of 5.72 mmHg (95% CI: 3.18-8.27 mmHg) and diastolic BP change of 6.09 mmHg (95% CI: 4.02-8.16 mmHg) at 40 weeks gestation when exposed to 50 μg/L compared to ≤ 1 μg/L arsenic. Participants with lower BMI exposed to drinking water manganese in the 2nd quartile (181-573 μg/L) had 1.04 mmHg higher mean diastolic BP (95% CI: 0.01-2.07 mmHg) at 40 weeks gestation compared to those in the 1st quartile (0.5-180 μg/L).

CONCLUSION

Arsenic exposures during pregnancy were consistently associated with increased average maternal systolic and diastolic BP. The effect of manganese on BP was less consistent.

Maternal blood pressure trajectories and associations with gestational age at birth: a functional data analytic approach

BACKGROUND

Research has revealed group-level differences in maternal blood pressure trajectories across pregnancy. These trajectories are typically constructed using clinical blood pressure data and multivariate statistical methods that are prone to bias and ignore the functional, dynamic process underlying a single blood pressure observation. The aim of this study was to use functional data analysis to explore blood pressure variation across pregnancy, and multivariate methods to examine whether trajectories are related to gestational age at birth.

METHODS

Clinical blood pressure observations were available from 370 women who participated in a longitudinal pregnancy cohort study conducted in Montreal, Quebec, Canada. Functional data analysis was used to smooth blood pressure data and then to conduct a functional principal component analysis to examine predominant modes of variation.

RESULTS

Three eigenfunctions explained greater than 95% of the total variance in blood pressure. The first accounted for approximately 80% of the variance and was characterized by a prolonged-decrease trajectory in blood pressure; the second explained 10% of the variance and captured a late-increase trajectory; and the third accounted for approximately 7% of the variance and captured a mid-decrease trajectory. The prolonged-decrease trajectory of blood pressure was associated with older, and late-increase with younger gestational age at birth.

CONCLUSION

Functional data analysis is a useful method to model repeated maternal blood pressure observations and many other time-related cardiovascular processes. Results add to previous research investigating blood pressure trajectories across pregnancy through identification of additional, potentially clinically important modes of variation that are associated with gestational age at birth.

Blood pressure adjustments throughout healthy and hypertensive pregnancy: A systematic review and meta-analysis

Gestational hypertensive complications are preceded by deviant hemodynamic adjustments affecting blood pressure. Our objective was to determine the timing and magnitude of changes in blood pressure during singleton normotensive and hypertensive pregnancies. PubMed (NCBI) and Embase (Ovid) databases were searched for relevant studies up to November 2019. Studies reporting original blood pressure measurements during pregnancy together with a non-pregnant reference measurement were included. Studies including women with a history of cardiovascular or metabolic disease, or women using antihypertensive drugs were excluded. Pooled mean differences between pregnant and non-pregnant women, and absolute blood pressure values were calculated for predefined gestational intervals in normotensive and hypertensive pregnancy, using a random-effects model. Meta-regression analysis was used to analyze group differences in adjustments. In early normotensive pregnancy, both systolic and diastolic blood pressure decreased, reaching their maximum reduction of -4 mmHg (95%CI -6 to -1 mmHg) and -4 mmHg (95%CI, -5 to -3 mmHg), respectively in the second trimester. Thereafter, blood pressure gradually increased towards non-pregnant values. All absolute blood pressure measurements throughout normotensive pregnancy were below 130/80 mmHg. In hypertensive pregnancies, only diastolic blood pressure decreased early in pregnancy. In conclusion, this meta-analysis showed a clinically moderate, but significant mid-pregnancy drop in blood pressure during normotensive pregnancy. Reference curves with absolute values underscore the current liberal cut-off limit for gestational hypertension. A lack of a mid-pregnancy systolic blood pressure drop might reflect increased vascular resistance in women destined to develop hypertensive pregnancy complications.

Association of pre-pregnancy body mass index and rate of weight gain during pregnancy with maternal indicators of cardiometabolic risk

BACKGROUND/OBJECTIVE

Changes in metabolism and extensive hemodynamic adjustments occur during normal pregnancy. The presence of maternal obesity imposes an overload to these physiological adaptations that may result in increased risk for the development of cardiometabolic complications during and after pregnancy. The aim of this study is to describe total cholesterol (TC), triglycerides (TG), glucose, and arterial blood pressure (BP) trajectories and to analyze the association of these cardiometabolic risk indicators during pregnancy with pre-pregnancy body mass index (pBMI) and monthly gestational weight gain (MGWG).

SUBJECTS/METHODS

A prospective cohort study of pregnant women was conducted in Mexico City. Monthly samples of blood were taken during clinical follow-up and biochemical and blood pressure were measured during each visit. Adjusted linear mixed-effect regression models were fit to describe the trajectories of these biomarkers during pregnancy and to analyze the association with pBMI and MGWG.

RESULTS

Seven hundred and twenty women were included of which 16.6% had pre-gestational obesity, 33.2% had pre-gestational overweight, 45.8% had normal pBMI and 4.4% had pre-gestational underweight. Women with pre-gestational obesity had higher lipids concentrations in the beginning of pregnancy (TC: [Formula: see text] = 33.08, p = 0.010; TG: [Formula: see text] = 31.29, p = <0.001) but the concentrations increased less than in women with normal pBMI (TC: [Formula: see text] = -14.18, p = 0.001; TG: [Formula: see text] = -5.42, p < 0.001). By the end of pregnancy, women with pre-gestational obesity had lower concentrations of lipids than women with normal pBMI. By contrast, women with pre-gestational obesity had higher glucose concentrations and higher BP levels than women with normal pBMI over pregnancy.

CONCLUSIONS

pBMI is differentially associated with longitudinal trajectories of maternal biochemical markers of cardiometabolic risk. MGWG did not significantly affect the biochemical indicators or BP trajectories. Our results suggest that pBMI is more relevant to predicting adverse cardiometabolic markers trajectories during pregnancy than MGWG.

Parameterization of the mid-trimester drop in blood pressure trajectory during pregnancy and its utility for predicting preeclampsia

OBJECTIVES

The purpose of this study was to parameterize mid-trimester drop in blood pressure (BP) trajectory during pregnancy and to evaluate its utility for predicting preeclampsia.

METHODS

To develop parametric models for BP trajectory during pregnancy, we used data from 7923 Chinese pregnant women with 24 810 routine antenatal care visits. Then, we evaluated the utility of BP trajectory parameters for predicting clinician-diagnosed preeclampsia in a separate sample of 3524 pregnant women from a randomized controlled trial of prenatal vitamin supplementation conducted in the same area. We focused on parameters related to the mid-trimester BP drop, including the gestational age and BP value at the nadir (lowest point), change in BP, velocity, and area under curve during two periods (from 12 weeks of gestation to the nadir and from the nadir to 33 weeks of gestation).

RESULTS

All participants in our analysis had a mid-pregnancy drop in their SBP, DBP, and mean arterial pressure (MAP) trajectories. There were high correlations (|r| > 0.90) among trajectory parameters of the same BP measure. The final prediction model included selective parameters of SBP, DBP, and MAP trajectories, prepregnancy BMI and gestational age at the first antenatal care visit. The area under the receiver-operating curve for predicting preeclampsia was 0.886 (95% confidence interval 0.846--0.926) in the training dataset and 0.802 (0.708--0.895) in the validation dataset.

CONCLUSION

Our novel BP trajectory parameters are informative and can predict preeclampsia at a clinically acceptable level.

Prevalence, placenta development, and perinatal outcomes of women with hypertensive disorders of pregnancy at Komfo Anokye Teaching Hospital

BACKGROUND

One of the most common medical problems associated with pregnancy is hypertension. Hypertensive disorders of pregnancy (HDP), which has been attributable to abnormal placentation may have adverse effects on both mother and foetus if left unchecked. The objective of this study was to determine the prevalence of this condition and its effect on placental morphology as well as maternal and perinatal outcomes.

MATERIALS AND METHODS

This was a prospective case-control study, conducted at Komfo Anokye Teaching Hospital (KATH), Ghana between February 2018 and July 2018. The progression of pregnancy in normotensive and hypertensive pregnant women, and the eventual perinatal outcomes were closely followed. Statistical analysis was performed using IMB-SPSS version 23. Associations were considered significant at p values of ≤ 0.05.

RESULTS

From a total of 214 deliveries recorded during the period of study, 84 (39.25%) were hypertensives. Forty four (52%) of the hypertensives had preeclampsia, 28 (33.3%) had gestational hypertension, 6 (7.1%) had eclampsia, 4 (4.8%) had chronic hypertension, and 2 (2.4%) had preeclampsia superimposed on chronic hypertension. The frequency of placental haematoma, placental infarction, and placental calcification in the normotensives were significantly (p = 0.001) lower than that of the hypertensives. The mean placental weight (p = 0.01), placental volume (p = 0.001), placental diameter (p = 0.03), and placental thickness (p = 0.001) of the normotensives were significantly higher than those of the hypertensives. The number of normotensives in whom labour was induced, who had their babies delivered by caesarean section, and who were admitted after they had given birth were significantly (p = 0.001) lower than that of hypertensives who underwent similar procedures. No stillbirths were recorded in the normotensives compared with four in the hypertensives. The number of babies delivered to the normotensives who were admitted to the NICU was significantly (p = 0.001) lower than those delivered by hypertensives.

CONCLUSION

There was a high prevalence of hypertensive disorders of pregnancy in the study site. Pregnant women who developed HDP are at a risk of developing placental abnormalities that adversely affected perinatal outcomes. These adverse effects can be curtailed by embarking on a vigorous health education drive.

Independent influences of maternal obesity and fetal sex on maternal cardiovascular adaptation to pregnancy: a prospective cohort study

Background/Objectives

Successful pregnancy requires the de novo creation of low-resistance utero-placental and feto-placental circulations and incomplete remodeling of this vasculature can lead to maternal or fetal compromise. Maternal BMI and fetal sex are known to influence vascular compliance and placental development, but it is unknown if these are independent or synergistic effects. Here we aim to investigate the impact of maternal obesity, fetal sex, and any interaction thereof on maternal cardiovascular adaptation to pregnancy, by assessing the physiological drop of uterine artery doppler pulsatility (UtA-PI) and umbilical artery doppler pulsatility index (UA-PI) over gestation.

Subjects/Methods

Nulliparous women with a singleton pregnancy participating in a prospective cohort study (n = 4212) underwent serial UtA-PI and UA-PI measurements at 20-, 28- and 36-weeks gestation. Linear mixed regression models were employed to investigate the influence of maternal BMI, fetal sex and interactions thereof on the magnitude of change in UtA-PI and UA-PI.

Results

Throughout gestation, UtA-PI was higher for male fetuses and UA-PI was higher for female fetuses. The physiological drop of UtA-PI was significantly smaller in overweight (change −24.3% [95%CI −22.3, −26.2]) and obese women (change −21.3% [−18.3, −24.3]), compared to normal-weight women (change −25.7% [−24.3, −27.0]) but did not differ by fetal sex. The physiological drop in UA-PI was greater for female than male fetuses (–32.5% [−31.5, −33.5] vs. −30.7% [−29.8, −31.7]) but did not differ by maternal BMI. No interactions between maternal BMI and fetal sex were found.

Conclusions

Maternal cardiovascular adaptation to pregnancy is independently associated with maternal BMI and fetal sex. Our results imply sexual dimorphism in both maternal cardiovascular adaptation and feto-placental resistance.

Pre-conception blood pressure and evidence of placental malperfusion

Background

Evidence of placental maternal vascular malperfusion is associated with significant perinatal outcomes such as preeclampsia, intrauterine growth restriction and preterm birth. Elevations in pre-pregnancy blood pressure increase the risk for poor perinatal outcomes; however, the evidence linking pre-pregnancy blood pressure and placental malperfusion is sparse.

Materials and methods

We conducted a retrospective case-control study of women with singleton gestations with placental evaluations who delivered at Magee-Womens Hospital in 2012. Charts from 100 deliveries with placental malperfusion lesions (vasculopathy, advanced villous maturation, infarct, or fibrin deposition) and 102 deliveries without placental malperfusion were randomly selected for screening. Blood pressure, demographic, and clinical data were abstracted from pre-pregnancy electronic medical records and compared between women with and without subsequent placental malperfusion lesions.

Results

Overall, 48% of women had pre-pregnancy records, and these were similarly available for women with and without placental malperfusion. Women with placental malperfusion demonstrated a reduction in their pre- to early pregnancy decrease in diastolic blood pressure (DBP). Adjusted for race, pre-pregnancy BMI, age, pre-conception interval, and gestational age at the first prenatal visit, the difference in pre- to early pregnancy DBP was significantly less in women with placental malperfusion compared to those without this pathologic finding (− 1.35 mmHg drop vs − 5.6mmg, p < 0.05).

Conclusion

A blunted early gestation drop in DBP may be a risk factor for placental malperfusion, perhaps related to early pregnancy vascular maladaptation. The ability of the electronic medical record to provide pre-pregnancy data serves as an underutilized approach to study pre-pregnancy health.

Ambulatory Blood Pressure Trajectory and Perceived Stress in Relation to Birth Outcomes in Healthy Pregnant Adolescents

OBJECTIVE

An early decline in resting blood pressure (BP), followed by an upward climb, is well documented and indicative of a healthy pregnancy course. Although BP is considered both an effector of stress and a clinically meaningful measurement in pregnancy, little is known about its trajectory in association with birth outcomes compared with other stress effectors. The current prospective longitudinal study examined BP trajectory and perceived stress in association with birth outcomes (gestational age (GA) at birth and birth weight (BW) percentile corrected for GA) in pregnant adolescents, a group at risk for stress-associated poor birth outcomes.

METHODS

Healthy pregnant nulliparous adolescents (n = 139) were followed from early pregnancy through birth. At three time points (13-16, 24-27, and 34-37 gestational weeks ±1 week), the Perceived Stress Scale was collected along with 24-hour ambulatory BP (systolic and diastolic) and electronic diary reporting of posture. GA at birth and BW were abstracted from medical records.

RESULTS

After adjustment for posture and pre-pregnancy body mass index, hierarchical mixed-model linear regression showed the expected early decline (B = -0.18, p = .023) and then increase (B = 0.01, p < .001) of diastolic BP approximating a U-shape; however, systolic BP displayed only an increase (B = 0.01, p = .010). In addition, the models indicated a stronger systolic and diastolic BP U-shape for early GA at birth and lower BW percentile and an inverted U-shape for late GA at birth and higher BW percentile. No effects of perceived stress were observed.

CONCLUSIONS

These results replicate the pregnancy BP trajectory from previous studies of adults and indicate that the degree to which the trajectory emerges in adolescence may be associated with variation in birth outcomes, with a moderate U-shape indicating the healthiest outcomes.

THE PREVALENCE OF UNDERWEIGHT, OVERWEIGHT AND OBESITY IN A ROMANIAN POPULATION IN THE FIRST TRIMESTER OF PREGNANCY - CLINICAL IMPLICATIONS

Context

Underweight, overweight and obesity are important global public health issues and risk factors for adverse perinatal outcomes.

Objective

To assess the distribution of the body mass index (BMI) in the Romanian obstetric population in the first trimester of pregnancy and its correlation with pregnancy outcomes. We also report the distribution of blood pressure (BP) parameters and their correlation with BMI.

Design

This retrospective study includes 9,064 women attending routine first trimester visit and ultrasound scan at 12.8(±0.6) gestational weeks. Characteristics, parity, method of conception, blood pressure (from 3,650 women), maternal weight and height, BMI and foetal ultrasound were recorded. Pregnancy outcomes were available for 1,607 deliveries. The Pearson correlation coefficient was assessed for each BMI group vs. blood pressure parameters, gestational age and birth weight. ANOVA analysis and post hoc tests were used to determine group differences. Linear regression was applied to estimate the contribution of BMI and gestational age to birth weight variance.

Results

In our population, 66.37% pregnant women had a normal BMI, 19.29% were overweight, and 7.56% were obese. There was a weak-to-medium positive correlation between BMI and blood pressure parameters, for all weight categories. The correlation between maternal BMI and birth weight was positive for normal and overweight.

Conclusions

Our findings highlight the need for more effective health strategies targeting reduction of weight-related problems in women of childbearing age.

Quantile regression analysis of modifiable and non-modifiable drivers' of blood pressure among urban and rural women in Ghana

High blood pressure is an increasingly problematic public health concern in many developing countries due to the associated cardiovascular and renal complications. This study set out to investigate the drivers of blood pressure among urban and rural women using the 2014 Ghana Demographic and Health Survey data. Diastolic blood pressure (DBP) and systolic blood pressure (SBP) were the outcomes of interest. Our findings showed that body mass index (BMI) had a significant positive effect on DBP and SBP in both urban and rural settings, with the largest effect occurring among women in the 75^th quantile. Arm circumference also had a positive effect on DBP and SBP across all quantiles in both settings. Age had an increasing positive effect along the entire conditional DBP and SBP distribution in both settings. Women who were pregnant had lower DBP and SBP relative to those who were not pregnant in both settings. These results highlight the important drivers of DBP and SBP, and the differential effects of these drivers on blood pressure (BP) among women in urban and rural settings. To increase their effectiveness, interventions to address high BP should take into account these differential effects.

Trimester-Specific Weight Gain and Midpregnancy Diastolic Blood Pressure Rebound During Normotensive Pregnancy

The longitudinal exposure-response relationship between trimester-specific gestational weight gain (GWG) and blood pressure (BP) during pregnancy is not well understood. We retrospectively assessed 1112 uncomplicated, normotensive pregnant women whose body weight and BP were measured from 12⁺⁰ to 40⁺⁰ weeks of gestation from a hospital-based cohort. By using growth curve modeling, a J-shaped pattern dominated diastolic BP (DBP) changing dynamics, with a midpregnancy drop at 20⁺⁰ to 22⁺⁰ weeks followed by a rebound. Using group-based trajectory modeling, 3 distinctive trajectories of DBP were identified: high-J shaped (18.5%), moderate-J shaped (48.3%), and low-J shaped (33.1%), as well as 3 distinctive GWG trajectories: high increasing (14.7%), moderate increasing (48.6%) and low increasing (36.8%). A temporal coincidence between the maximal rate of GWG and DBP transition from its nadir to rebound was observed during 20⁺⁰ to 22⁺⁰ weeks. Moreover, women in the high-increasing GWG group had the highest probability of being in the high-J DBP group. The GWG rate during the late midsecond trimester (22⁺⁰ to 26⁺⁰ weeks) was consistently associated with an elevated DBP level: for every 200 g/wk increase, the multivariable-adjusted odds ratio was 1.27 (95% confidence interval, 1.13-1.43) for the trajectory shift to the high-J group and 1.20 (95% confidence interval, 1.07-1.35) for the occurrence of diastolic prehypertension after 37⁺⁰ weeks. Furthermore, adding a trimester-specific GWG rate (22⁺⁰ to 26⁺⁰ weeks) contributed to the incremental yield for the prediction of diastolic prehypertension after 37⁺⁰ weeks. Our results thus provide the timing and extent of gestational weight control relevant to the optimized BP level during pregnancy.

Does pre-pregnancy BMI determine blood pressure during pregnancy? A prospective cohort study

OBJECTIVES

To evaluate if pre-pregnancy body mass index (BMI) determines blood pressure throughout pregnancy and to explore the role of gestational weight gain in this association. In addition, the effects of pre-pregnancy BMI and gestational weight gain on the occurrence of gestational hypertension and pre-eclampsia were investigated.

DESIGN

Prospective cohort study.

SETTING

Maternal and child health primary care referral centre, Jakarta, Indonesia.

POPULATION AND MEASUREMENTS

2252 pregnant women visiting Budi Kemuliaan Hospital and its branch for regular antenatal care visits from July 2012 to April 2015. Pre-pregnancy BMI (kg/m(2)) was based on self-reported pre-pregnancy weight and measured height at first visit. Gestational weight gain was calculated as weight at the day of delivery minus the pre-pregnancy weight. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured during pregnancy at every visit. Linear mixed models were used to analyse this relation with repeated blood pressure measures as the outcome and pre-pregnancy BMI as the predictor. When looking at gestational hypertension and pre-eclampsia as outcomes, (multiple) logistic regression was used in the analysis.

RESULTS

Independent of pre-pregnancy BMI, SBP and DBP increased by 0.99 mm Hg/month and 0.46 mm Hg/month, respectively. Higher pre-pregnancy BMI was associated with higher pregnancy SBP (0.25 mm Hg/kg/m(2); 95% CI 0.17 to 0.34; p<0.01) and DBP (0.18 mm Hg/kg/m(2); 0.13 to 0.24; p<0.01) in adjusted analysis. Every 1 kg/m(2) higher pre-pregnancy BMI was associated with 6% and 9% higher odds for gestational hypertension (adjusted OR (aOR) 1.06; 95% CI 1.03 to 1.09; p<0.01) and pre-eclampsia (aOR 1.09; 1.04 to 1.14; p<0.01). Accounting for gestational weight gain did not attenuate these associations.

CONCLUSIONS

Pre-pregnancy BMI determines the level, but not the change, of blood pressure in pregnancy and is linked to higher odds for gestational hypertension and pre-eclampsia, independent of gestational weight gain.

Relationship between body mass index and mean arterial pressure in normotensive and chronic hypertensive pregnant women: a prospective, longitudinal study

Background

Being overweight is associated with both higher systolic blood pressure (SBP) and diastolic blood pressure (DBP) during pregnancy and increased risk of gestational hypertensive disorders. The objective of this study was to determine and quantify the effect of body mass index (BMI) on mean arterial pressure (MAP) at several time points throughout pregnancy in normotensive (NT) and chronic hypertensive pregnant (HT) women.

Methods

A prospective longitudinal study was carried out in 461 singleton pregnancies (429 low-risk and 32 with chronic arterial hypertension), with measurements taken at the 1^st, 2^nd, and 3^rd trimesters and at delivery. Linear mixed-effects regression models were used to evaluate the time-progression of BMI, SBP, DBP and MAP during pregnancy (NT vs. HT). The longitudinal effect of BMI on MAP, adjusted for the hypertensive status, was investigated by the same methodology.

Results

BMI consistently increased with time in both NT and HT women. In contrast, MAP decreased during the first half of pregnancy, after which it increased until the moment of delivery in both groups. A 5-unit increase in BMI was predicted to produce an increase of approximately 1 mmHg in population MAP values. This effect is independent from the time period and from hypertensive status.

Conclusions

In both NT and HT pregnant women, MAP is strongly (and significantly) influenced by increases in BMI.

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.

Blood Pressure Variation Throughout Pregnancy According to Early Gestational BMI: A Brazilian Cohort

Background

The maternal cardiovascular system undergoes progressive adaptations throughout pregnancy, causing blood pressure fluctuations. However, no consensus has been established on its normal variation in uncomplicated pregnancies.

Objective

To describe the variation in systolic blood pressure (SBP) and diastolic blood pressure (DBP) levels during pregnancy according to early pregnancy body mass index (BMI).

Methods

SBP and DBP were measured during the first, second and third trimesters and at 30-45 days postpartum in a prospective cohort of 189 women aged 20-40 years. BMI (kg/m²) was measured up to the 13^th gestational week and classified as normal-weight (<25.0) or excessive weight (≥25.0). Longitudinal linear mixed-effects models were used for statistical analysis.

Results

A decrease in SBP and DBP was observed from the first to the second trimester (β_SBP=-0.394; 95%CI: -0.600- -0.188 and β_DBP=-0.617; 95%CI: -0.780- -0.454), as was an increase in SBP and DBP up to 30-45 postpartum days (β_SBP=0.010; 95%CI: 0.006-0.014 and β_DBP=0.015; 95%CI: 0.012-0.018). Women with excessive weight at early pregnancy showed higher mean SBP in all gestational trimesters, and higher mean DBP in the first and third trimesters. Excessive early pregnancy BMI was positively associated with prospective changes in SBP (β_SBP=7.055; 95%CI: 4.499-9.610) and in DBP (β_DBP=3.201; 95%CI: 1.136-5.266).

Conclusion

SBP and DBP decreased from the first to the second trimester and then increased up to the postpartum period. Women with excessive early pregnancy BMI had higher SBP and DBP than their normal-weight counterparts throughout pregnancy, but not in the postpartum period.

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

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 nulliparous 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.

Modelling childhood growth using fractional polynomials and linear splines

BACKGROUND

There is increasing emphasis in medical research on modelling growth across the life course and identifying factors associated with growth. Here, we demonstrate multilevel models for childhood growth either as a smooth function (using fractional polynomials) or a set of connected linear phases (using linear splines).

METHODS

We related parental social class to height from birth to 10 years of age in 5,588 girls from the Avon Longitudinal Study of Parents and Children (ALSPAC). Multilevel fractional polynomial modelling identified the best-fitting model as being of degree 2 with powers of the square root of age, and the square root of age multiplied by the log of age. The multilevel linear spline model identified knot points at 3, 12 and 36 months of age.

RESULTS

Both the fractional polynomial and linear spline models show an initially fast rate of growth, which slowed over time. Both models also showed that there was a disparity in length between manual and non-manual social class infants at birth, which decreased in magnitude until approximately 1 year of age and then increased.

CONCLUSIONS

Multilevel fractional polynomials give a more realistic smooth function, and linear spline models are easily interpretable. Each can be used to summarise individual growth trajectories and their relationships with individual-level exposures.

Established preeclampsia risk factors are related to patterns of blood pressure change in normal term pregnancy: findings from the Avon Longitudinal Study of Parents and Children

OBJECTIVE

Hypertension during pregnancy is one of the diagnostic criteria for preeclampsia. We investigated the pattern of blood pressure (BP) change across pregnancy and associations of risk factors for preeclampsia with BP changes in normal pregnancy.

METHODS

We examined repeat antenatal BP measurements (median 14 per woman) of 11,789 women from the Avon Longitudinal Study of Parents and Children cohort with a live-term birth and no evidence of preeclampsia or previous hypertension. Linear spline random effects models with knots at 18, 30 and 36 weeks gestation described changes in BP with gestational age.

RESULTS

On average, SBP and DBP decreased slowly until 18 weeks and rose from 18 weeks onwards, with increasing rate at 30 weeks and then again at 36 weeks. In obese women, BP was higher at 8 weeks and rose more slowly between 18 and 30 weeks and more rapidly between 30 and 36 weeks than in normal-weight women. Nulliparous women had higher BP at 8 weeks and faster increases in DBP from 30 weeks and SBP from 36 weeks onwards than multiparas. Women who smoked throughout pregnancy had lower BP at 8 weeks and throughout pregnancy; women who only smoked in the first trimester soon attained the same pattern of change as never smokers. In twin pregnancies, BP rose more rapidly from 30 weeks onwards than in singleton pregnancies.

CONCLUSION

Established preeclampsia risk factors are associated with higher BP in early pregnancy and faster BP increases later in gestation in normal pregnancy, suggesting a continuum of risk.

Blood pressure and heart rate variability complexity analysis in pregnant women with hypertension

BACKGROUND

In this work, we perform a comparative analysis of blood pressure and heart rate variability complexity during pregnancy between normal, hypertensive, and preeclamptic women.

METHODS AND RESULTS

A total of 563 short electrocardiographic (10 min) records were obtained from 217 pregnant women (135 normal, 55 hypertensive, and 27 preeclamptic) during several gestational ages in sitting position. We used a mixed unbalanced model for the longitudinal statistical analysis and besides the conventional spectral analysis, we applied Lempel-Ziv complexity, sample entropy, approximated entropy, and detrended fluctuation analysis in the complexity measurement.

CONCLUSIONS

The obtained results revealed significant differences between pathological and normal states with important considerations related to pregnancy adaptability and evolution as well as the relationship of complexity and blood pressure with factors such as maternal age, familial history of diabetes or hypertension, and parity.