The effect of obesity on heart rate (heart period) and physiologic parameters during pregnancy

Maternal high BMI: Sex-dimorphic alterations in maternal and offspring stress indices

Maternal body mass index (BMI) influences pregnancy and birth outcomes along with child metabolic and neurodevelopmental health and fetal sex may be a moderating factor in these effects. Alternations in autonomic nervous system (ANS) functioning, identified in heart rate (HR) measurements, could present early markers of these prenatal programming effects in both the mother and the developing fetus. This study examines the associations between pre-pregnancy BMI and maternal and fetal ANS functioning and infant postnatal behavioral outcomes stratified by fetal sex. Pregnant women (N=176) were recruited at gestational week (GW) T1: 12-22 and categorized into Normal (BMI< 25) or High BMI (BMI > 25). Women attended laboratory sessions at T2: GW 23-28, and T3: GW 34-36 to assess maternal and fetal HR and HR variability (HRV) at baseline and after a stressor at T3. Infant behavior was assessed at 4 months using the Infant Behavior Questionnaire-Revised. Women with high BMI bearing female fetuses had higher HR and lower HRV at both gestational time points. Later in the third trimester, female fetuses of high BMI women exhibited lower HRV when challenged with a stressor. At 4 months, female infants were rated as having lower scores on the Orienting/Regulatory scale. Our findings provide evidence of female sex-specific programming of maternal pre-pregnancy BMI on maternal ANS regulation and neurodevelopment identified in-utero and continuing into early infancy.

Changes in Heart Rate, Heart Rate Variability, Breathing Rate, and Skin Temperature throughout Pregnancy and the Impact of Emotions-A Longitudinal Evaluation Using a Sensor Bracelet

(1) Background: Basic vital signs change during normal pregnancy as they reflect the adaptation of maternal physiology. Electronic wearables like fitness bracelets have the potential to provide vital signs continuously in the home environment of pregnant women. (2) Methods: We performed a prospective observational study from November 2019 to November 2020 including healthy pregnant women, who recorded their wrist skin temperature, heart rate, heart rate variability, and breathing rate using an electronic wearable. In addition, eight emotions were assessed weekly using five-point Likert scales. Descriptive statistics and a multivariate model were applied to correlate the physiological parameters with maternal emotions. (3) Results: We analyzed data from 23 women using the electronic wearable during pregnancy. We calculated standard curves for each physiological parameter, which partially differed from the literature. We showed a significant association of several emotions like feeling stressed, tired, or happy with the course of physiological parameters. (4) Conclusions: Our data indicate that electronic wearables are helpful for closely observing vital signs in pregnancy and to establish modern curves for the physiological course of these parameters. In addition to physiological adaptation mechanisms and pregnancy disorders, emotions have the potential to influence the course of physiological parameters in pregnancy.

Impact of Adverse Gestational Milieu on Maternal Cardiovascular Health

Cardiovascular disease affects 1% to 4% of the nearly 4 million pregnancies in the United States each year and is the primary cause of pregnancy-related mortality. Adverse pregnancy outcomes are associated with cardiovascular complications during pregnancy persisting into the postpartum period. Recently, investigations have identified an altered sex hormone milieu, such as in the case of hyperandrogenism, as a causative factor in the development of gestational cardiovascular dysfunction. The mechanisms involved in the development of cardiovascular disease in postpartum women are largely unknown. Animal studies have attempted to recapitulate adverse pregnancy outcomes to investigate causal relationships and molecular underpinnings of adverse gestational cardiac events and progression to the development of cardiovascular disease postpartum. This review will focus on summarizing clinical and animal studies detailing the impact of adverse pregnancy outcomes, including preeclampsia, gestational diabetes mellitus, and maternal obesity, on gestational cardiometabolic dysfunction and postpartum cardiovascular disease. Specifically, we will highlight the adverse impact of gestational hyperandrogenism and its potential to serve as a biomarker for maternal gestational and postpartum cardiovascular dysfunctions.

Impact of maternal obesity on neonatal heart rate and cardiac size

BACKGROUND

Maternal obesity may increase offspring risk of cardiovascular disease. We assessed the impact of maternal obesity on cardiac structure and function in newborns as a marker of fetal cardiac growth.

METHODS

Neonates born to mothers of healthy weight (body mass index (BMI) 20-25 kg/m2, n=56) and to mothers who were obese (BMI ≥30 kg/m2, n=31) underwent 25-minute continuous ECG recording and non-sedated, free-breathing cardiac MRI within 72 hours of birth.

RESULTS

Mean (SD) heart rate during sleep was higher in infants born to mothers who were versus were not obese (123 (12.6) vs 114 (9.8) beats/min, p=0.002). Heart rate variability during sleep was lower in infants born to mothers who were versus were not obese (SD of normal-to-normal R-R interval 34.6 (16.8) vs 43.9 (16.5) ms, p=0.05). Similar heart rate changes were seen during wakefulness. Left ventricular end-diastolic volume (2.35 (0.14) vs 2.54 (0.29) mL/kg, p=0.03) and stroke volume (1.50 (0.09) vs 1.60 (0.14), p=0.04) were decreased in infants born to mothers who were versus were not obese. There were no differences in left ventricular end-systolic volume, ejection fraction, output or myocardial mass between the groups.

CONCLUSION

Maternal obesity was associated with increased heart rate, decreased heart rate variability and decreased left ventricular volumes in newborns. If persistent, these changes may provide a causal mechanism for the increased cardiovascular risk in adult offspring of mothers with obesity. In turn, modifying antenatal and perinatal maternal health may have the potential to optimise long-term cardiovascular health in offspring.

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.

Maternal Weight, Weight Gain, and Metabolism are Associated with Changes in Fetal Heart Rate and Variability

OBJECTIVE

Prepregnancy obesity and extensive weight gain can lead to diseases in the offspring later in life. The aim of this study was to evaluate the effect of anthropometric and metabolic factors on the fetal autonomic nervous system (ANS) in uncomplicated pregnancies.

METHODS

A total of 184 pregnant women in the second or third trimester were included, and for 104 women, maternal insulin sensitivity (ISI) was determined. Fetal heart rate (HR) and heart rate variability (HRV) were determined by magnetic recording. Associations of maternal prepregnancy BMI, weight gain, and ISI with fetal HR and HRV were evaluated by ANCOVA, partial correlation, and mediation analysis.

RESULTS

HR was increased and HRV decreased in fetuses of mothers with overweight or obesity in comparison to normal-weight mothers. Fetal HR was negatively correlated with maternal weight gain. Maternal prepregnancy BMI was positively correlated with fetal high frequency and was negatively correlated with low frequency and low/high frequency ratio. Maternal ISI showed a negative correlation with fetal HR.

CONCLUSIONS

The results show that the fetal ANS is sensitive to alterations of prepregnancy BMI, weight changes, and glucose metabolism. These findings highlight the importance of the intrauterine environment on the developing ANS and the possible programming of obesity.

Obesity in pregnancy causes a volume overload in third trimester

BACKGROUND

Obesity is a major risk factor for cardiovascular diseases. In this study, we aimed to investigate the maternal circulatory differences during pregnancy between obese and normal weight women.

MATERIALS AND METHODS

The functioning of the maternal circulation (arteries, veins, heart and body fluid) was assessed by ECG-Doppler ultrasound, impedance cardiography (ICG) and bio-impedance during pregnancy in obese women (BMI ≥30 kg/m² ) and normal weight, nonobese women (BMI 20-25 kg/m² ). In this observational study, 232 assessments were performed in the obese group, whereas 919 assessments were performed in the nonobese group.

RESULTS

Relative to nonobese women, the overall cardiovascular function in obese women during first and second trimester is consistent with a high volume/low-resistance circulation. In third trimester, cardiac output of obese women decreases from 9.2 (8.2-10.7) L/min to 8.5 (7.6-9.6) L/min (P = .037) whereas this is not true in the nonobese women (from 7.8 (7-8.5) L/min to 7.8 (6.8-8.9) L/min, P = .536). Simultaneously, the persistently lower peripheral vascular resistance in obese vs nonobese women disappears (880 (761-1060) dyn.sec/cm⁵ vs 928 (780-1067).

CONCLUSIONS

The circulatory gestational adaptations between nonobese and obese women were generally similar. The findings in the third trimester suggest that a pregnancy in obese women start as a state of high volume/low resistance, gradually shifting to a volume overload with decrease of cardiac output and disappearance of low vascular resistance. This evolution makes obese women vulnerable for gestational hypertensive diseases.

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.

Influence of maternal exercise on fetal heart response during labor and delivery

OBJECTIVES

The purpose of this study was to determine if prenatal exercise alters the maternal and fetal heart responses during labor and delivery. We hypothesized that fetuses of exercising mothers would exhibit a lower baseline heart rate (HR), increased HR variability (HRV), and no differences in fetal heart accelerations and decelerations.

DESIGN

This study employed a cross-sectional design.

METHODS

The Modifiable Physical Activity Questionnaire was used for group classification. Exercising women were those participating in 30 minutes of moderate-to-vigorous exercise at least 3×/week throughout the entire pregnancy. Women achieving a lower dose of exercise were classified as non-exercisers. Cardiotocography recordings during the first hour of labor and delivery assessed fetal baseline HR, HRV, accelerations, decelerations, and contractions. ANCOVA analyses were performed to assess group differences in these outcomes and were adjusted for maternal body mass index.

RESULTS

Thirty-one women were included in the analyses. No group mean differences were found for maternal and fetal characteristics, except for maternal age (EX: mean (SD) 28.5 (±4.6y) vs NON-EX: 24.1 (±1.2y)). After controlling for body mass index, no statistical differences in maternal HR response (β = 3.9, SE = 5.0, 95%CI -6.4-14.2) or fetal HR response (β = 3.9, SE = 2.5, 95%CI -1.2-9.11), accelerations and decelerations (β= -0.03, SE = 0.4, 95%CI -0.9-0.8; β= -0.10, SE = 0.4, 95%CI -0.8-0.9, respectively), or HRV (β = 0.6, SE = 1.7, 95%CI -2.8-4.0) were observed.

CONCLUSIONS

Based on the findings of this study, we found no evidence that maternal exercise during pregnancy was associated with maternal or fetal HR response during labor and delivery. These data suggest maternal exercise may not elicit positive or negative effects on maternal and fetal cardiovascular responses to the physiological stress of labor and delivery.

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.

Elevated resting heart rate and reduced orthostatic tolerance in obese humans

BACKGROUND

Obesity is linked with numerous physiological impairments; however, its impact on orthostatic tolerance (OT) remains unknown. This study tested the hypothesis that OT is reduced in obese individuals, and that reduced heart rate (HR) reserve and impaired cerebral autoregulation contribute to impaired OT.

METHODS

Eleven obese (8 females) and 22 non-obese (10 females) individuals were exposed to incremental lower body negative pressure (LBNP) to presyncope while HR, arterial blood pressure, and cerebral perfusion (middle cerebral artery blood velocity; MCA V mean) were measured. OT was quantified with a cumulative stress index (CSI).

RESULTS

OT was reduced in obese subjects, and there was an inverse relationship between body mass index (BMI) and OT (R = -0.47). HR was higher at rest and during each level of LBNP completed by all subjects. Similar peak HR (HRpeak) during LBNP between obese and non-obese subjects resulted in obese having a higher %peak HR at rest and at each stage of LBNP compared. Relationships existed for BMI and resting %HRpeak (R = 0.45) and resting %HRpeak and CSI (R = -0.52). Despite lower CSI in obese, MCA V mean and indices of cerebral autoregulation were similar between groups at all time points.

CONCLUSIONS

These data suggest that OT is reduced in obese and a higher resting HR, but not impaired regulation of cerebral perfusion, may contribute to this reduction.

Disrupted prenatal maternal cortisol, maternal obesity, and childhood wheeze. Insights into prenatal programming

RATIONALE

Exploring prenatal factors influencing childhood wheeze may inform programming mechanisms.

OBJECTIVES

We examined associations among prenatal maternal cortisol profiles, maternal obesity, and repeated wheeze up to age 2 years (n = 261).

METHODS

Salivary cortisol was collected five times per day over 3 days at 29.0 ± 4.9 weeks gestation. Mothers were categorized as obese (body mass index ≥ 30 kg/m(2)) versus nonobese (body mass index < 30 kg/m(2)). Using logistic regression, we examined the influence of log-transformed cortisol metrics (level at each time point, morning rise, diurnal and afternoon slopes) and obesity on wheeze adjusting for covariates. Linear mixed models were implemented to examine associations between cortisol trajectories and wheezing. Interactions between maternal cortisol and obesity were considered.

MEASUREMENTS AND MAIN RESULTS

Mothers were primarily minority (56.5% Hispanic, 24.1% African American), 61% had less than or equal to 12 years of education, 34% were obese, and 8.4% of children had repeated wheeze. An interquartile range increase in mean log cortisol at bedtime (odds ratio, 2.2; 95% confidence interval, 1.09-4.09) and maternal obesity (odds ratio, 3.43; 95% confidence interval, 1.26-9.35) were independently associated with wheeze. Linear mixed models revealed an association between a flatter afternoon slope (slower decline in log cortisol per hour) and repeated wheeze in children of obese mothers (children with [-0.017 change] and without [-0.061 change] wheeze [P = 0.009 for time × wheeze interaction]), but not in children of nonobese mothers (with [-0.050 change] and without [-0.061 change] wheeze [P = 0.51]).

CONCLUSIONS

Maternal prenatal cortisol disruption and obesity were independently associated with children's wheeze. Obese women with adverse cortisol profiles were most likely to have children with repeated wheeze.

Blood pressure changes during pregnancy: impact of race, body mass index, and weight gain

OBJECTIVE

To investigate the effect of race, body mass index (BMI), and weight gain on blood pressure in pregnancy and postpartum.

STUDY DESIGN

Secondary analysis of pregnant women aged 14 to 25 who received prenatal care at a university-affiliated public clinic in New Haven, Connecticut and delivered singleton term infants (n = 418). Longitudinal multivariate analysis was used to evaluate blood pressure trajectories from pregnancy through 12 weeks postpartum.

RESULTS

Obese and overweight women had significantly higher blood pressure readings as compared with women with normal BMI (all p < 0.05). African American women who had high pregnancy weight gain had the greatest increase in mean arterial and diastolic blood pressures in pregnancy and postpartum.

CONCLUSION

Blood pressure trajectories in pregnancy and postpartum are significantly affected by race, BMI, and weight gain. Given the young age of this cohort, targeted efforts must be made for postpartum weight reduction to reduce cardiovascular risk.

Twenty-four-hour ambulatory blood pressure monitor heart rate: a potential marker for gestational hypertension in at-risk women

We prospectively correlated the 24-hour ambulatory blood pressure measurements (ABPM) to conventional sphygmomanometer blood pressure measurements (CSM) in women at risk for gestational hypertensive disorders (GHTNDs) and identified predictive factors from ABPM for GHTND. We analyzed 73 women with ≥ 1 risk factor for developing a GHTND. Using both the CSM and ABPM, the systolic blood pressure, diastolic blood pressure, mean arterial pressure (MAP), and heart rate (HR) were measured for 24 hours during three periods (14 to 24 weeks; 24 to 32 weeks; and 33 weeks to delivery). Correlation between the CSM and ABPM lessened as pregnancy progressed. Seventeen (25%) of women developed a GHTND. MAP variability increased in the GHTND group versus those without a GHTND. The odds of developing a GHTND increased 1.5 times for every 1 beat per minute increase in the ABPM 24-hour HR at visit 1 and reversed by visit 3. In women at risk for a GHTND, CSM and ABPM correlate less well as pregnancy advances. HR changes in at-risk women may be a marker for the development of a GHTND and may reflect increased sympathetic activity and/or decreased baroreceptor sensitivity.

Obesity and pregnancy: clinical management of the obese gravida

In recent years, the prevalence of obesity in the United States has risen dramatically, especially among women of reproductive age. Research that has specifically evaluated pregnancy outcomes among obese parturients has allowed for a better understanding of the myriad adverse perinatal complications that are observed with significantly greater frequency in the obese pregnant population. The antepartum, intrapartum, intraoperative, postoperative, and postpartum periods are all times in which the obese pregnant woman is at greater risk for adverse maternal-fetal outcomes, compared with her ideal bodyweight counterpart. Comorbid medical conditions that commonly are associated with obesity further accentuate perinatal risks. All obese pregnant women should be counseled regarding these risks, and strategies should be used to improve perinatal outcome whenever possible. Obese women of reproductive age ideally should be counseled before conception and advised to achieve ideal bodyweight before pregnancy.

The effects of exercise conditioning in normal and overweight pregnant women on blood pressure and heart rate variability

Pre-pregnancy obesity is a risk factor for preeclampsia, gestational diabetes, and hypertension. Regular exercise during pregnancy has been shown to decrease the risk of these obstetrical complications. The purpose of this prospective study was to measure the effects of an exercise program in normal-weight and overweight/obese pregnant women on blood pressure (BP) and cardiac autonomic function, determined by heart rate variability (HRV) and baroreflex sensitivity (BRS). Twenty-two sedentary pregnant women, recruited at 20 weeks gestational age (GA), were grouped as normal weight or overweight/obese. They were systematically assigned to an exercise (walking) group or control (nonwalking) group after the first participants were randomly assigned. Women in the walking groups participated in a 16-week, low-intensity walking program. BP, HRV, and BRS were measured at rest and during exercise at the beginning (20 weeks GA) and end (36 weeks GA) of the walking program. Results indicated that women in the control groups (especially overweight women) showed changes in BP, HRV, and BRS over pregnancy that were not seen in the walking group. Overweight women in the control group increased resting systolic BP by 10 mmHg and diastolic BP by 7 mmHg. HRV declined in the control group but not in the walking group. A reduction in BRS and R-R interval at rest was found in all groups except the walking normal-weight group. The results suggest that an exercise program could attenuate the increase in BP and the loss of parasympathetic tone associated with pregnancy, especially in overweight women.