Maternal kidney function during pregnancy: systematic review and meta-analysis.

OBJECTIVES: To review systematically current literature on kidney function changes during pregnancy, in order to estimate the extent of adaptation over the course of both healthy physiological and complicated singleton pregnancies, and to determine healthy pregnancy reference values. METHODS: PubMed (NCBI) and EMBASE (Ovid) electronic databases were searched, from inception to July 2017, for studies on kidney function during uncomplicated and complicated pregnancies. Included studies were required to report a non-pregnant reference value of kidney function (either in a non-pregnant control group or as a prepregnancy or postpartum measurement) and a pregnancy measurement at a predetermined and reported gestational age. Kidney function measures assessed were glomerular filtration rate (GFR) measured by inulin clearance, GFR measured by creatinine clearance and serum creatinine level. Pooled mean differences between pregnancy measurements and reference values were calculated for predefined intervals of gestational age in uncomplicated and complicated pregnancies using a random-effects model described by DerSimonian and Laird. RESULTS: Twenty-nine studies met the inclusion criteria and were included in the analysis. As early as the first trimester, GFR was increased by up to 40-50% in physiological pregnancy when compared with non-pregnant values. Inulin clearance in uncomplicated pregnancy was highest at 36-41 weeks, with a 55.6% (53.7; 95% CI, 44.7-62.6 mL/min) increase when compared with non-pregnant values, and creatinine clearance was highest at 15-21 weeks' gestation, with a 37.6% (36.6; 95% CI, 26.2-46.9 mL/min) increase. Decrease in serum creatinine level in uncomplicated pregnancy was most prominent at 15-21 weeks, with a 23.2% (-0.19; 95% CI, -0.23 to -0.15 mg/dL) decrease when compared with non-pregnant values. Eight studies reported on pregnancies complicated by a hypertensive disorder. Meta-regression analysis showed a significant difference in all kidney function parameters when comparing uncomplicated and hypertensive complicated pregnancies. CONCLUSIONS: In healthy pregnancy, GFR is increased as early as the first trimester, as compared with non-pregnant values, and the kidneys continue to function at a higher rate throughout gestation. In contrast, kidney function is decreased in hypertensive pregnancy. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Metabolic syndrome after pregnancies complicated by pre-eclampsia or small-for-gestational-age: a retrospective cohort.

OBJECTIVE: To study the prevalence of metabolic syndrome in women after a pregnancy complicated by pre-eclampsia or small-for-gestational-age (SGA), both epitomes of placental syndrome. DESIGN: A retrospective cohort study. SETTING: Single tertiary centre for maternal medicine in the Netherlands. POPULATION: Women with a history of pre-eclampsia in absence of SGA (n = 742) or pregnancy complicated by normotensive SGA (n = 147) between 1996 and 2010. METHODS: Women were routinely screened for underlying cardiometabolic and cardiovascular risk factors at least 6 months postpartum. Logistic regression analysis was used to calculate the odds ratio and adjusted odds ratio for each group. Adjustments were made for age, maternal height, smoking, parity, and interval between delivery and measurement. MAIN OUTCOME MEASURES: Prevalence of the metabolic syndrome. RESULTS: The prevalence of the metabolic syndrome in our population was two-fold higher for women with a history of pre-eclampsia (13.9%) compared with women with a history of SGA (7.6%). Calculated odds ratios for metabolic syndrome, fasting insulin, HOMA, and microalbuminuria were all higher for women with a history of pre-eclampsia compared with women with SGA. This difference persisted after adjustment for confounding factors: metabolic syndrome (adjusted odds ratio, aOR 2.11; 95% confidence interval, 95% CI 1.00-4.47) and hyperinsulinaemia (aOR 1.78; 95% CI 1.13-2.81) insulin resistance (HOMAIR ; aOR 1.80; 95% CI 1.14-2.86). Microalbuminuria (aOR 1.58; 95% CI 0.85-2.93) did not reach the level of significance after adjustment for confounding factors. CONCLUSIONS: A history of pre-eclampsia, rather than SGA, was associated with metabolic syndrome, suggesting that it relates to maternal rather than fetal etiology of placental syndrome.

Early pregnancy circulatory adaptation and recurrent hypertensive disease: an explorative study.

INTRODUCTION: Hypertensive pregnancy disorders are assumed to be preceded by defective spiral artery remodeling. Whether this localized aberration at the implantation site affects the initial maternal systemic cardiovascular and renal adaptation to pregnancy is unclear. We explored in a high-risk population, whether the initial systemic maternal adaptation to pregnancy differs between women who do and do not develop a recurrent hypertensive disorder later on in pregnancy. METHODS: We enrolled 61 normotensive women with a previous hypertensive disorder of pregnancy and subdivided them into 2 subgroups, based on whether or not their next pregnancy remained uneventful (n = 33) or became complicated by a recurrent hypertensive disorder (n = 28). We measured before pregnancy and again at 18 ± 2 weeks of gestation cardiac output, blood pressure, plasma volume, creatinine clearance, and calculated total peripheral vascular resistance from cardiac output and blood pressure. RESULT: Both subgroups responded to pregnancy with an increase in cardiac output, plasma volume, heart rate, and creatinine clearance, and a decrease in blood pressure and total peripheral vascular resistance. Women who developed a recurrent hypertensive disorder differed from their counterparts with an uneventful next pregnancy by smaller pregnancy-induced increases in creatinine clearance (19% vs. 31%, P = .035) and cardiac output (10% vs. 20%, P = .035), respectively. CONCLUSION: The initial systemic cardiovascular and renal adaptations to pregnancy in women who develop a recurrent gestational hypertensive disorder differ from those in their counterparts with an uneventful next pregnancy by smaller rises in creatinine clearance and cardiac output.