Effect of bariatric surgery on maternal cardiovascular system

OBJECTIVE

Bariatric surgery is a successful treatment for sustainable weight loss and has been associated with improvement in cardiovascular function. Pregnancy after bariatric surgery is becoming increasingly common; however, little is known about the maternal cardiovascular system postsurgery. The aim of this study was to investigate maternal cardiovascular adaptation to pregnancy in women with previous bariatric surgery, compared with that in women with no history of weight-loss surgery and an early-pregnancy body mass index (BMI) similar to the presurgery BMI of the postbariatric women.

METHODS

This was a prospective, observational, longitudinal study conducted from April 2018 to June 2020 including 30 pregnant women who had undergone bariatric surgery and 30 who had not, matched for presurgery BMI. Participants were seen at three timepoints during pregnancy: 12-14, 20-24 and 30-32 weeks' gestation. At all visits, maternal blood pressure (BP) was measured and cardiac geometry and function were assessed using two-dimensional (2D) transthoracic echocardiography. On a subset of patients (15 in each group), 2D speckle tracking was performed to assess global longitudinal and circumferential strain. Offline analysis was performed, and multilevel linear mixed-effects models were used for all comparisons.

RESULTS

Compared with the no-surgery group, and across all trimesters, pregnant women with previous bariatric surgery had lower BP, heart rate and cardiac output and higher peripheral vascular resistance (P < 0.01 for all). Similarly, the postbariatric group demonstrated more favorable cardiac geometry and diastolic indices, including lower left ventricular mass, left atrial volume and relative wall thickness, together with higher E-wave/A-wave flow velocity across the mitral valve and higher mitral velocity (E') at the lateral and medial annulus on tissue Doppler imaging (P < 0.01 for all). There was no difference in ejection fraction, although global longitudinal strain was lower in postbariatric women (P < 0.01), indicating better systolic function.

CONCLUSION

Our findings indicate better maternal cardiovascular adaptation in women with previous bariatric surgery compared with presurgery BMI-matched pregnant women with no history of weight-loss surgery. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

The effect of mode of delivery and duration of labour on subsequent pregnancy outcomes: a retrospective cohort study

OBJECTIVE

To assess whether delivery mode and duration of labour in a first labour of spontaneous onset is associated with gestational length, delivery mode and neonatal outcome in the subsequent pregnancy.

STUDY DESIGN

Retrospective analysis of prospectively collected data.

SETTING

15 Maternity units in North West London (1988-2000).

POPULATION

30 840 women with spontaneous onset of labour in pregnancy 1 and a subsequent birth reported in the same database.

METHODS

Assessment of outcomes by mode of delivery in pregnancy 1, restricting the analysis to the difference in the gestational length between pregnancy 1 and 2.

MAIN OUTCOME MEASURES

Gestational length, mode of delivery and neonatal unit admission in pregnancy 2.

RESULTS

Caesarean section (CS) in the first or second stage of labour in pregnancy 1 was associated with pregnancy 2 being a median of 5 and 8 days shorter and a preterm birth rate of 6.0% and 10.1%, respectively, whereas following a normal or instrumental vaginal birth in pregnancy 1, the median duration was similar, with preterm delivery rates of 4.5% and 3.9%. In all, 56.2% of women with a CS in pregnancy 1 had a repeat CS and 12.5% of their babies were admitted to a neonatal unit, compared with 5.3% of women with vaginal birth. Longer labours were associated with shorter gestations in pregnancy 2.

CONCLUSIONS

Compared with vaginal birth, an emergency CS in the first-term pregnancy is associated with a shorter gestational length, increased rate of repeat CS and increased risk of NNU admission in the next pregnancy.

TWEETABLE ABSTRACT

An emergency caesarean section in the first-term pregnancy affects the duration and outcome of the next pregnancy.

Fetal growth and fetoplacental circulation in pregnancies following bariatric surgery: a prospective study

OBJECTIVE

To investigate the intrauterine fetal growth pattern and fetoplacental circulation in pregnancies following bariatric surgery.

DESIGN

Prospective study.

SETTING

Maternity Unit, UK.

POPULATION

One hundred and sixty-two pregnant women; 54 with previous bariatric surgery and 108 with no surgery but similar booking body mass index.

METHODS

Participants were seen at 11-14, 20-24, 30-33 and 35-37 weeks of gestation and an oral glucose tolerance test (OGTT) was performed at 27-30 weeks. Fetal head and abdominal circumference (AC), femur length (FL), estimated fetal weight (EFW) and fetoplacental Dopplers were measured at three time-points in pregnancy. Birthweight (BW) was recorded. Variables were modelled after adjustment for maternal/pregnancy characteristics. Model estimates are reported as posterior means and quantile-based 90% credible intervals (CrI).

MAIN OUTCOME MEASURES

Fetal biometry, fetoplacental Doppler, BW.

RESULTS

Compared with the no surgery group, the post-bariatric surgery group had lower EFW during gestation (up to -120 g; [-189 g, -51 g] lighter) at 35-37 weeks, with smaller AC and FL. Similarly, infants of mothers with previous bariatric surgery had lower average BW [-202 g [-330 g, -72 g] lighter). Overall, there was no difference in the fetoplacental Doppler indices between groups but maternal glucose levels at OGTT were positively correlated with third-trimester EFW and BW.

CONCLUSIONS

Fetuses of women with previous bariatric surgery are smaller during pregnancy and at birth, compared with those of women without such surgery, and this may be related to the lower maternal glucose levels seen in the former population. The fetoplacental circulation appears not to be altered by maternal weight loss surgery.

TWEETABLE ABSTRACT

Offspring of post-bariatric women are smaller during pregnancy and at birth but this is not due to placental insufficiency.

First-trimester uterine artery Doppler examination in pregnancies complicated by gestational diabetes mellitus with or without pre-eclampsia

OBJECTIVES

To assess first-trimester placental perfusion, reflected in the uterine artery (UtA) pulsatility index (PI), in pregnancies complicated by gestational diabetes mellitus (GDM), with or without pre-eclampsia (PE), compared with those unaffected by GDM.

METHODS

UtA-PI was measured at 11 + 0 to 13 + 6 weeks' gestation in 1037 singleton pregnancies that subsequently developed GDM and in 56 649 normoglycemic controls. The measured mean UtA-PI was converted to multiples of the expected normal median (MoM), corrected for maternal weight, racial origin and gestational age, and the median MoM values in the two groups were compared.

RESULTS

The incidence of PE was higher in pregnancies with GDM than in controls (4.0% vs 2.3%, respectively; P =  0.001). However, there were no significant differences in the median UtA-PI MoM between the groups (1.00 (interquartile range (IQR), 0.82-1.21) vs 1.00 (IQR, 0.81-1.21); P = 0.73). The median UtA-PI in patients who developed PE was higher than in those who did not develop PE, regardless of the development of GDM.

CONCLUSIONS

First-trimester placental perfusion, as assessed by UtA Doppler examination, is not impaired in women who subsequently develop GDM. The increased prevalence of PE in women with GDM cannot be attributed to impaired placentation.

The effect of maternal characteristics and gestational diabetes on birthweight

OBJECTIVE

To examine the effect of maternal characteristics, including advancing maternal age, body mass index (BMI), racial origin and development of gestational diabetes mellitus (GDM), on birthweight and the interactions between these factors.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

Fifteen maternity units in North West London, between 1988 and 2000.

POPULATION

A cohort of 130 549 pregnant women.

METHODS

Multivariate regression analysis.

OUTCOME MEASURES

Birthweight z-scores in non-GDM and GDM groups within three main racial groups (white European, black and South Asian women).

RESULTS

Babies born to women with GDM were heavier compared with those born to women with no GDM in all racial groups. In black women with GDM the birthweight z-scores were 0.805 higher, in South Asian women the scores were 0.618 higher and in white European women the scores were 0.437 higher, compared with the respective non-GDM group (P < 0.001 for both comparisons versus white European women), and these differences were much greater at high rather than at low maternal BMIs. Advancing maternal age, increasing BMI, highest diastolic blood pressure, Castair's index, racial group and presence of GDM or smoking were each, individually, significantly associated with birthweight z-scores (P < 0.001 for all variables). After adjusting for possible confounding factors, BMI was positively associated with birthweight z-scores within all racial groups (P < 0.001 for all), irrespective of glycaemic status, but its effect was much greater in women with GDM, particularly in those of non-White origin. After adjusting for possible confounding factors, advancing maternal age was only positively associated with birthweight in women of white European and South Asian racial origin who did not suffer from GDM (P < 0.001 for both).

CONCLUSION

Gestational diabetes mellitus strongly accentuates the effect of maternal BMI on birthweight, especially within non-white populations.

Maternal serum 25-hydroxyvitamin D levels at 11(+0) -13(+6) weeks in pregnant women with diabetes mellitus and in those with macrosomic neonates

OBJECTIVE

To investigate whether maternal serum levels of 25-hydroxyvitamin D [25(OH)D] in the first trimester are altered in pregnant women with pre-existing type 2 diabetes, women who subsequently develop gestational diabetes mellitus (GDM) and women who deliver large for gestational age (LGA) neonates compared with normoglycaemic pregnant women who deliver an appropriate for gestational age (AGA) neonate.

DESIGN

Case-control study.

SETTING

Antenatal clinic.

POPULATION

Singleton pregnancies at 11(+0) -13(+6) weeks, including 50 women with type 2 diabetes, 100 women who subsequently developed GDM, 50 nondiabetic women who subsequently delivered LGA neonates and 1000 nondiabetic controls who delivered AGA neonates.

METHODS

Maternal serum total 25(OH)D levels were measured in the four groups of pregnancies. Multiple regression analysis in the controls was used to identify factors among maternal characteristics with a significant contribution to the levels of serum 25(OH)D, so that the values in all cases were expressed as a multiple of the median (MoM) in the controls.

MAIN OUTCOME MEASURES

Comparison of MoM 25(OH)D in the four groups.

RESULTS

In controls, significant independent contributions to the serum level of 25(OH)D were provided by maternal age, body mass index, smoking status, racial origin and season of sampling. The median and interquartile range (IQR) of serum 25(OH)D in the type 2 diabetes group (1.01; IQR, 0.68-1.47 MoM), GDM group (0.93; IQR, 0.67-1.23 MoM) and LGA group (0.97; IQR, 0.67-1.25 MoM) were not significantly different from those in the controls (0.99; IQR, 0.71-1.33 MoM) (overall P = 0.643).

CONCLUSIONS

The first-trimester maternal serum level of 25(OH)D is not altered in women with type 2 diabetes, those who develop GDM or those who deliver LGA neonates.

An analysis of the interrelationship between maternal age, body mass index and racial origin in the development of gestational diabetes mellitus

OBJECTIVE

To examine the individual association between advancing maternal age, body mass index (BMI) and racial origin with the development of gestational diabetes mellitus (GDM) and the interaction between these factors.

DESIGN

Retrospective study.

SETTING

Fifteen maternity units in northwest London between 1988 and 2000.

POPULATION

The study included 1688 women who developed GDM and 172,632 who did not. All women were nulliparous. BMI was calculated at first antenatal visit and maternal age and racial origin (White European, Black African, Black Caribbean or South Asian) were self-reported.

METHODS

Binary logistic regression analysis.

MAIN OUTCOME MEASURES

Development of GDM within each racial group.

RESULTS

There was a strong positive association between advancing maternal age and increasing BMI, individually, and the development of GDM (P < 0.01 for both). Compared with White Europeans aged 20-24 years, the odds ratios for GDM development were significantly higher in women older than 30 years if they were White Europeans (P < 0.001), older than 25 years if they were Black Africans (P < 0.001) and older than 20 years if they were South Asians (P < 0.001). The odds ratios for GDM development were significantly higher in Black Africans and South Asians (P < 0.001 for both) irrespective of BMI, compared with White Europeans with normal BMI.

CONCLUSION

Maternal age and BMI interact with racial group in relation to the prevalence of GDM. Both factors are important in the development of GDM, particularly so in Black African and South Asian women.

First trimester maternal uterine artery Doppler examination in HIV-positive women

OBJECTIVES

The aim of the current study was to assess the effect of maternal HIV infection, treated or untreated, on the degree of placental invasion, as assessed by the pulsatility index of the uterine arteries during a Doppler examination at 11(+0) -13(+6) weeks' gestation.

METHODS

This was a nested case-control study in which a uterine artery Doppler examination was performed in the first trimester in 76 HIV-positive women. Each woman was matched with 30 HIV-negative women. As the pulsatility index of the uterine arteries depends on a number of maternal and fetal characteristics, its values in each case and control were expressed as multiples of the median (MoM) of the unaffected group.

RESULTS

Among the 76 HIV-positive women, 33 (43.4%) were on antiretroviral treatment at the time of the Doppler examination, including 14 women (42.4%) on nucleoside reverse transcriptase inhibitors (NRTIs) and a protease inhibitor, 18 women (54.5%) on NRTIs and a nonnucleoside reverse transcriptase inhibitor and one woman (3.1%) on monotherapy. Compared with the HIV-negative women, the HIV-positive women were more likely to be heavier (P<0.01), to be of African origin (P<0.01), to be nonsmokers (P=0.01) and to deliver smaller neonates earlier (P<0.01). The median adjusted pulsatility index of the uterine arteries was not statistically different between the cases and controls [1.07; interquartile range (IQR) 0.85-1.24 MoM vs. 0.99; IQR 0.81-1.20 MoM; P= 0.28] or, in HIV-positive women, between those receiving and not receiving antiretroviral treatment (P=0.12).

CONCLUSIONS

HIV-positive women with uncomplicated pregnancies have normal placental perfusion in the first trimester of pregnancy.

Maternal arterial stiffness in pregnancies affected by Type 1 diabetes mellitus

AIM

There is little information about maternal central haemodynamics and arterial stiffness in pregnancies affected by Type 1 diabetes mellitus. The aim of the current study was to investigate whether maternal arterial stiffness is altered in pregnant women with Type 1 diabetes mellitus compared with women with uncomplicated pregnancies.

METHODS

This was a cross-sectional study involving 37 pregnant women without diabetes and 37 pregnant women with Type 1 diabetes mellitus during the second trimester of pregnancy. Maternal wave reflection (augmentation index) and pulse wave velocity of the carotid-femoral and carotid-radial part of the arterial tree were assessed non-invasively using applanation tonometry.

RESULTS

Pregnant women with normal pregnancies and Type 1 diabetes mellitus had similar augmentation index (3.7 +/- 12.8 vs. 5.1 +/- 12.6%, P = 0.6), even after adjusting for possible confounders. Within the group of diabetic women, augmentation index was associated with duration of diabetes (P = 0.003, r(2) = 0.22) but not with glycated haemoglobin. Pulse wave velocities were similar between the two groups of women (carotid-femoral: 5.6 +/- 0.9 vs. 5.7 +/- 1.1 m/s, P = 0.4; carotid-radial: 7.4 +/- 1.2 vs. 7.8 +/- 1 m/s, P = 0.1). In the diabetic women there was no significant association between the pulse wave velocities and either duration of diabetes or glycated haemoglobin.

CONCLUSIONS

Pregnancy in women with Type 1 diabetes mellitus is not associated with altered maternal systemic arterial stiffness. However, maternal wave reflections increase with the duration of diabetes.

Maternal endothelial function and serum concentrations of placental growth factor and soluble endoglin in women with abnormal placentation

OBJECTIVES

To determine whether maternal serum concentrations of placental growth factor (PlGF) and soluble endoglin (sEng) are altered in women who subsequently develop pre-eclampsia (PE) or have small-for-gestational-age (SGA) infants, and whether these changes are associated with maternal endothelial dysfunction.

METHODS

Maternal serum PlGF and sEng were measured in two groups of pregnant women at 23-25 weeks' gestation: Group A (n = 40), with normal uterine artery Doppler waveforms and Group B (n = 43) with abnormal Doppler. Maternal endothelial dysfunction was assessed by flow-mediated dilatation (FMD) of the brachial artery. Comparisons between groups were performed using one-way analysis of variance.

RESULTS

In Group B, 16 women had normal outcome, 15 delivered SGA infants and 12 developed PE. Women who developed PE had lower levels of PlGF (154.8 +/- 150.8 vs. 423.3 +/- 230.5 pg/mL; P < 0.001) (data given as mean +/- SD) and higher levels of sEng (8.1 (7.0-14.1) vs. 6.5 (4.9-7.9) pg/mL; P < 0.05) (data given as median (interquartile range)) than Group A. Similar were the findings in women who delivered SGA infants. In women who subsequently developed PE, there was no correlation between FMD and either PlGF or sEng.

CONCLUSIONS

Maternal serum concentrations of PlGF and sEng are altered in women who develop PE. However, these alterations do not correlate directly with maternal endothelial dysfunction.

Endothelial nitric oxide synthase gene polymorphism and maternal vascular adaptation to pregnancy

A common polymorphism of the endothelial NO synthase gene that predicts a Glu298Asp amino acid substitution in the mature protein has been associated with cardiovascular disorders in which NO bioactivity is impaired. However, the influence of this polymorphism on endothelial function is unknown. Healthy pregnancy is associated with enhanced endothelium-dependent, flow-mediated dilation (FMD) of the brachial artery, a response mediated by NO. In this study, we investigated the effect of the endothelial NO synthase Glu298Asp polymorphism on endothelium-dependent vasodilation in early pregnancy, making the hypothesis that any genotype-dependent differences in NO generation would be more marked during pregnancy, when the production of NO is upregulated. FMD of the brachial artery was recorded during the first trimester in 139 healthy women with normal singleton pregnancies genotyped for the Glu298Asp variant of endothelial NO synthase. Maternal FMD exhibited a codominant inverse relation with the number of Asp298 alleles (r=-0.21, P=0.01). Among homozygotes for endothelial NO synthase Asp298, FMD (7.99+/-1.46%) was significantly lower than that observed among individuals homozygous for endothelial NO synthase Glu298 (10.12+/-3.44) (P=0.002). In a backward stepwise multiple regression analysis, vessel size (P<0.0001) and Glu298Asp polymorphism (P=0.01) were significantly and independently correlated with FMD. Our findings indicate that the endothelial NO synthase Glu298Asp polymorphism is associated with differences in endothelium-dependent dilation at 12-week gestation and are the first to implicate genetic factors in the normal vascular adaptation to pregnancy. They also provide a potential mechanism linking the endothelial NO synthase polymorphism with the development of cardiovascular disorders and have implications for understanding the genetic basis of preeclampsia.

Twin chorionicity and pre-eclampsia

OBJECTIVE

To determine whether the incidence of pre-eclampsia is different in dichorionic compared to monochorionic twin pregnancies.

METHODS

The study involved 666 twin pregnancies resulting in two live births after 24 weeks of gestation. Ultrasound examination at 10-14 weeks of gestation demonstrated that 171 (25.7%) were monochorionic and 495 (74.3%) were dichorionic twins. Pregnancy outcome information regarding the development of pre-eclampsia was obtained from the maternity units. The incidence of pre-eclampsia in the dichorionic and monochorionic twin pregnancies was compared.

RESULTS

The incidence of pre-eclampsia in monochorionic twin pregnancies (9.4%) was not significantly different from that in dichorionic pregnancies (7.3%) ( P = 0.48). Multiple logistic regression revealed that chorionicity has no effect on the development of pre-eclampsia after adjusting for maternal age, ethnic group, maternal smoking, parity and gestational age at delivery ( P = 0.6; odds ratio for monochorionic compared with dichorionic twin pregnancies, 1.19; 95% confidence interval, 0.61-2.3).

CONCLUSION

In twin pregnancies chorionicity does not affect the incidence of pre-eclampsia.

Assessment of endothelial function in normal twin pregnancy

OBJECTIVE

To assess the maternal endothelial function in normal twin pregnancy.

DESIGN

Cross-sectional study.

SUBJECTS

Endothelial function was investigated in 74 women with normal twin pregnancy at 11-30 weeks of gestation and the results were compared to previous reported findings in 98 women with normal singleton pregnancy and 19 non-pregnant controls.

METHODS

Endothelial function was assessed by measuring the changes of the brachial artery diameter in response to reactive hyperemia (flow-mediated dilatation) using external high resolution ultrasound.

RESULTS

Flow-mediated dilatation of the brachial artery in both twin and singleton pregnancies was significantly higher than in non-pregnant women (P = 0.002 and P = 0.02, respectively). However, there was no significant difference in flow-mediated dilatation between women with twin and singleton pregnancy (9.61 +/- 4.36 vs. 8.84 +/- 3.18, P = 0.38). Resting vessel size, baseline flow and reactive hyperemia did not change significantly with gestation in twin pregnancy and were similar to values in singleton pregnancies and controls.

CONCLUSION

Our findings indicate that although in pregnancy endothelial function is enhanced, this change may not be affected by the number of fetoplacental units present.

Non-invasive assessment of endothelial function in normal pregnancy

OBJECTIVE

To assess endothelial function in normal pregnancy by non-invasive methods.

METHODS

Flow-mediated dilatation of the brachial artery was measured by ultrasonography in 157 women with normal singleton pregnancies between 10 and 40 weeks' gestation and 19 non-pregnant controls.

RESULTS

Flow-mediated dilatation in the non-pregnant controls was 6.42 +/- 2.45%. In pregnant women, between 10 and 30 weeks, the mean flow-mediated dilatation (8.84 +/- 3.18%) was significantly higher than the non-pregnant controls (P = 0.002), but after 30 weeks of gestation there was a decrease to prepregnancy levels. Resting vessel diameter and blood flow were significantly increased in pregnancy, mainly after 30 weeks' gestation (P < 0.001, P < 0.001, respectively). Flow-mediated dilatation was significantly correlated to resting vessel diameter and reactive hyperemia.

CONCLUSION

Normal pregnancy is associated with enhanced endothelial function which is apparent from at least 10 weeks' gestation.