Seasonal variation in the hypertensive disorders of pregnancy in Denmark

Association between embryo transfer season and the risks of hypertensive disorders of pregnancy and gestational diabetes mellitus

PURPOSE

To explore the impact of seasonal variations on the risks of hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM) in women who undergo in vitro fertilization (IVF) treatment.

METHODS

We retrospectively included a total of 21,469 women who achieved singleton delivery during their first cycles of IVF, the risks of HDP and GDM were compared in different seasonal groups according to the time of embryo transfer and the time of oocyte retrieval.

RESULTS

After adjustment via multivariable logistic regression, women who underwent embryo transfer in spring with the expected date of confinement in winter had a higher risk of HDP (4.9% vs. 3.8%; adjusted odds ratio (aOR), 1.34; 95% confidence interval (CI), 1.09-1.64; P = 0.005) than those underwent embryo transfer in winter with the expected date of confinement in autumn. There were no seasonal variations in the risk of HDP according to the time of oocyte retrieval or in the risk of GDM regardless of the time of embryo transfer or the time of oocyte retrieval. After subgroup analysis, the seasonal variations in the risk of HDP remained in frozen embryo transfer (FET) cycles but not in fresh embryo transfer (FreET) cycles.

CONCLUSIONS

The risk of HDP was increased in women who underwent embryo transfer in spring compared to those who underwent embryo transfer in winter. The risk of HDP is more likely to be affected by the season at the time of embryo transfer in FET cycles compared to FreET cycles.

Season of conception and risk of hypertensive disorder during pregnancy

BACKGROUND

Hypertensive Disorder during Pregnancy (HDP) is the most prevalent obstetric conditions in maternal health, but the etiology of most cases remains unexplained. Seasonal variations in the conception of HDP may offer insights into the potential seasonal-specific risk factors.

METHODS

Data were sourced from the China's National Maternal Near Miss Surveillance System (NMNMSS) between January 1, 2012, and December 31, 2021. HDP status was ascertained from the diagnostic records over 400 medical institutions. The conception date was estimated based on the delivery date and duration of gestation length, and the season of conception, were categorised as winter (December to February), spring (March to May), summer (June to August), and fall (September to November). Odd ratios were calculated separately using the logistic regression model.

RESULTS

Among the 14,073,565 pregnant women analysed, 3.98% met the study's criteria for HDP as defined in the present study. Maternal conception in spring was associated with a 10% increased risk of HDP (aOR, 1.10 [95% CI, 1.08-1.12]) compared with summer conceptions. Elevated risk of HDP was observed for maternal individuals conceiving in February, March, April, May, and June according to analyses conducted for specific months. The associations were slightly stronger in the subgroup of women diagnosed with gestational hypertension and preeclampsia. Significant disparities exist in this association among the diverse Köppen-Geiger climate zones.

CONCLUSION

Significant seasonal variations in the risk for HDP were observed across a range of maternal characteristics, HDP subtypes, and climatc zones. These findings imply the necessity of considering seasonally fluctuating environmental factors in the etiological investigation of HDP.

CLINICAL TRIAL NUMBER

Not applicable.

Seasonal variation in home blood pressure during pregnancy and frequency of hypertensive disorders of pregnancy: a multicenter prospective study of home blood pressure measurements in pregnant women using information technology

This multicenter prospective study investigated seasonal variation in home blood pressure (HBP) during pregnancy and its association with the frequency of hypertensive disorders of pregnancy (HDP) and developed trimester-specific upper limits of HBP according to season. Low-risk women with singleton pregnancies were recruited at six university hospitals and three maternity clinics. HBP was measured by a sphygmomanometer twice daily and recorded online using a mobile application. HBP was evaluated according to season (winter, spring, summer, and autumn) and gestational age. Of 705 women recruited, 603 were finally included. Mean diastolic HBP values were lowest in summer and highest in winter throughout pregnancy (mean difference between summer and winter, 3.5-4.6 mmHg). Mean systolic HBP values were also lowest in summer and highest in winter except during the early period of the second trimester (mean difference between summer and the season with the highest value, 2.5-3.4 mmHg). HDP was diagnosed in 32 women (5.3%). The risk of HDP was significantly higher in women who delivered in spring and autumn but not in winter compared with summer. The rounded upper limit of HBP was 120/80 mmHg in the first trimester, 120/75 mmHg in the second trimester, and 125/80 mmHg in the third trimester for summer and 125/85 mmHg, 125/80 mmHg, and 130/85 mmHg, respectively, for other seasons. Systolic and diastolic HBP were lowest in summer throughout pregnancy. Seasonal variation should be considered when interpreting HBP and the risk of HDP during pregnancy.

Hypertensive disorders of pregnancy in Hunan Province, China, 2012-2022

Objective

To explore the relationship between hypertensive disorders of pregnancy (HDP) and adverse pregnancy outcomes and explore the risk factors for HDP.

Methods

Data were obtained from the Maternal Near-Miss Surveillance System in Hunan Province, China, 2012-2022. Chi-square trend tests (χ2 trend) were used to determine trends in prevalence by year. Unadjusted odds ratios (uORs) were used to examine the association between HDP and adverse pregnancy outcomes. Multivariate logistic regression analysis (method: Forward, Wald, α = 0.05) and adjusted odds ratios (aORs) were used to identify risk factors for HDP.

Results

Our study included 780,359 pregnant women, and 38,397 women with HDP were identified, with a prevalence of 4.92% (95% CI 4.87-4.97). The prevalence of preeclampsia-eclampsia, gestational hypertension, chronic hypertension, and chronic hypertension with superimposed preeclampsia was 2.28% (95% CI 2.25-2.31), 2.04% (95% CI 2.00-2.07), 0.43% (95% CI 0.41-0.44), and 0.18% (95% CI 0.17-0.19), respectively. From 2012 to 2022, the prevalence of HDP increased from 3.11 to 7.39%, showing an upward trend (χ 2 trend = 2220.88, p < 0.01). HDP was associated with the following adverse pregnancy outcomes: maternal deaths (uOR =4.05), maternal near-miss (uOR =6.37), preterm birth (uOR =2.51), stillbirth and neonatal death (uOR =1.45), low birthweight (uOR =4.37), abruptio placentae (uOR =4.45), uterine atony (uOR =1.49), retained placenta (uOR =1.54), puerperal infections (uOR =2.14), abdominal surgical site infections (uOR =2.50), urinary tract infections (uOR =1.60), upper respiratory tract infections (uOR =1.75), heart disease (uOR =2.76), embolism (uOR =2.66), liver disease (uOR =1.25), anemia (uOR =1.38), diabetes mellitus (uOR =2.35), renal disease (uOR =4.66), and pulmonary disease (uOR =4.70, p < 0.05). Results of multivariate logistic regression analysis showed risk factors for HDP: maternal age > 30 years (aOR > 1, p < 0.05), gravidity > = 4 (aOR =1.10, 95% CI 1.05-1.14), primipara (aOR > 1, p < 0.05), and previous cesarean sections (aOR =1.27, 95% CI 1.24-1.31).

Conclusion

The prevalence of HDP was relatively high in Hunan Province. HDP was associated with many adverse pregnancy outcomes. Advanced maternal age, high gravidity, primipara, and previous cesarean section were risk factors for HDP.

Winter, spring, summer or fall: temporal patterns in placenta-mediated pregnancy complications-an exploratory analysis

PURPOSE

Placenta-mediated pregnancy complications, like growth restriction and hypertensive disorders, are leading causes of maternal, fetal and neonatal morbidity and mortality in high-income countries. The purpose was to investigate if there is a seasonal variation in placenta-mediated pregnancy complications (small for gestational age, intrauterine growth restriction, preeclampsia, preterm birth and intrauterine fetal death).

METHODS

This is a Danish cohort study including all singleton deliveries at gestational week 22 up to and including week 41 conceived from December 2006 to November 2016 (N = 555,459). We used statistical process control charts to visualize data and to test for patterns of non-random variation in data over time for pregnancies with risk factors (BMI, diabetes, in vitro fertilization, maternal age > 40 years, primipara, previous caesarean and smoking) and each of the following outcome: fetal growth restriction, hypertensive disorders, preterm birth and intrauterine fetal death. The study was approved by the Danish Data Protection agency; REG-039-2019.

RESULTS

We found a seasonal pattern in hypertensive disorders during pregnancy with dips in pregnancies conceived in the fall season and highest risk by conception in the spring and summer season. We found no apparent seasonality in cases of preterm delivery, small for gestational age and intrauterine mortality. Individual risk factors (e.g. smoking and obesity) for placenta-mediated complicated over time were in consistency with the general trends.

CONCLUSIONS

We found a significant seasonal variation in the risk of hypertensive disorders of pregnancy with highest risk by conception in the spring and summer season. This study found no seasonal variation in other placenta-mediated complications.

Associations between extreme temperature exposure and hypertensive disorders in pregnancy: a systematic review and meta-analysis

BACKGROUND

Hypertensive disorders in pregnancy (HDP) are a major cause of maternal mortality and morbidity. Recent studies indicated that pregnant women are the most vulnerable populations to ambient temperature influences, but it affected HDP with inconsistent conclusions. Our objective is to systematically review whether extreme temperature exposure is associated with a changed risk for HDP.

METHOD

We searched PubMed, EMBASE, Web of Science and Cochrane Library databases. We included cohort or case control studies examining the association between extreme temperature exposure before or during pregnancy and HDP. Heat sources such as saunas and hot baths were excluded. We pooled the odds ratio (OR) to assess the association between extreme temperature exposure and preeclampsia or eclampsia.

RESULTS

Fifteen studies involving 4,481,888 patients were included. Five studies were included in the meta-analysis. The overall result demonstrated that in the first half of pregnancy, heat exposure increases the risk of developing preeclampsia or eclampsia and gestational hypertension, and cold exposure decreases the risk. The meta-analysis revealed that during the first half of pregnancy, heat exposure increased the risk of preeclampsia or eclampsia (OR 1.54, 95% confidence interval (CI): 1.10, 2.15), whereas cold exposure decreased the risk (OR 0.90, 95% CI: 0.84, 0.97).

CONCLUSION

The ambient temperature is an important determinant for the development of HDP, especially for preeclampsia or eclampsia. The effects of extreme temperatures may be bidirectional during the different trimesters of pregnancy, which should be evaluated by future studies. This review provided hints of temperature regulation in HDP administration.

Bayesian spatiotemporal modelling for disease mapping: an application to preeclampsia and gestational diabetes in Florida, United States

Morbidities generally show patterns of concentration that vary by space and time. Disease mapping models are useful in estimating the spatiotemporal patterns of disease risks and are therefore pivotal for effective disease surveillance, resource allocation, and the development of prevention strategies. This study considers six spatiotemporal Bayesian hierarchical models based on two spatial conditional autoregressive priors. It could serve as a guideline on the development and application of Bayesian hierarchical models to assess the emerging risk trends, risk clustering, and spatial inequality trends, with estimation of covariables' effects on the interested disease risk. The method is applied to the Florida Birth Record data between 2006 and 2015 to study two cardiovascular risk factors: preeclampsia and gestational diabetes. High-risk clusters were detected in North Central Florida for preeclampsia and in Central Florida for gestational diabetes. While the adjusted disease trend was stable, spatial inequality peaked in 2011-2012 for both diseases. Exposure to PM2.5 at first or/and second trimester increased the risk of preeclampsia and gestational diabetes, but the magnitude is less severe compared to previous studies. In conclusion, this study underscores the significance of selecting appropriate disease mapping models in estimating the intricate spatiotemporal patterns of disease risk and suggests the importance of localized interventions to reduce health disparities. The result also identified an opportunity to study potential risk factors of preeclampsia, as the spike of risk in North Central Florida cannot be explained by current covariables.

A Mobile Clinical Decision Support System for High-Risk Pregnant Women in Rural India (SMARThealth Pregnancy): Pilot Cluster Randomized Controlled Trial

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death in women in India. Early identification is crucial to reducing deaths. Hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM) carry independent risks for future CVD, and antenatal care is a window to screen and counsel high-risk women. In rural India, community health workers (CHWs) deliver antenatal and postnatal care. We developed a complex intervention (SMARThealth Pregnancy) involving mobile clinical decision support for CHWs and evaluated it in a pilot cluster randomized controlled trial (cRCT).

OBJECTIVE

The aim of the study is to co-design a theory-informed intervention for CHWs to screen, refer, and counsel pregnant women at high risk of future CVD in rural India and evaluate its feasibility and acceptability.

METHODS

In phase 1, we used qualitative methods to explore community priorities for high-risk pregnant women in rural areas of 2 diverse states in India. In phase 2, informed by behavior change theory and human-centered design, we used these qualitative data to develop the intervention components and implementation strategies for SMARThealth Pregnancy in an iterative process with end users. In phase 3, using mixed methods, we evaluated the intervention in a cRCT with an embedded qualitative substudy across 4 primary health centres: 2 in Jhajjar district, Haryana, and 2 in Guntur district, Andhra Pradesh.

RESULTS

SMARThealth Pregnancy embedded a total of 15 behavior change techniques and included (1) community awareness programs; (2) targeted training, including point-of-care blood pressure and hemoglobin measurement; and (3) mobile clinical decision support for CHWs to screen women in their homes. The intervention focused on 3 priority conditions: anemia, HDP, and GDM. The evaluation involved a total of 200 pregnant women, equally randomized to intervention or enhanced standard care (control). Recruitment was completed within 5 months, with minimal loss to follow-up (4/200, 2%) at 6 weeks postpartum. A total of 4 primary care doctors and 54 CHWs in the intervention clusters took part in the study. Fidelity to intervention practices was 100% prepandemic. Over half the study population was affected by moderate to severe anemia at baseline. The prevalence of HDP (2.5%) and GDM (2%) was low in our study population. Results suggest a possible improvement in mean hemoglobin (anemia) in the intervention group, although an adequately powered trial is needed. The model of home-based care was feasible and acceptable for pregnant or postpartum women and CHWs, who perceived improvements in quality of care, self-efficacy, and professional recognition.

CONCLUSIONS

SMARThealth Pregnancy is an innovative model of home-based care for high-risk pregnant women during the transitions between antenatal and postnatal care and adult health services. The use of theory and co-design during intervention development facilitated acceptability of the intervention and implementation strategies. Our experience has informed the decision to initiate a larger-scale cRCT.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03968952; https://clinicaltrials.gov/ct2/show/NCT03968952.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.3389/fgwh.2021.620759.

The Association Between Season and Hypertensive Disorders in Pregnancy: a Systematic Review and Meta-analysis

There is increasing and inconsistent evidence of a relationship between hypertensive disorders in pregnancy (HDPs) and season of delivery or conception. In this systematic review and meta-analysis, we assessed the association between season and HDPs. The review protocol was registered in PROSPERO (CRD42021285539). Four databases, the Cochrane Library, PubMed, EMBASE, and Web of Science, were searched until September 29th, 2021. Two authors extracted data independently and used the Newcastle-Ottawa quality assessment scale (NOS) to evaluate study quality. A random effects model and the Mantel-Haenszel method were used to calculate pooled Odds ratios (ORs) and 95% confidence intervals (95% CIs). Subgroup analyses and sensitivity analyses were performed to find the source of heterogeneity and Begg's funnel plot and Egger's test were used to check for the risk of publication bias. Finally, twenty articles were included in the systematic review, and 11 articles were included in the meta-analysis. The quantitative analysis of the association between delivery season and HDPs showed that the odds of HDPs was higher in women who delivered in winter than in those who delivered in summer (OR = 1.18, 95% CI 1.02-1.38, P < 0.001) and all other seasons (OR = 1.17, 95% CI 1.03-1.34, P < 0.001). In the qualitative analysis of the association between conception season and HDPs, four of seven studies suggested that women who conceived in summer had a higher risk of HDPs than those who conceived in other seasons. Based on the evidence to date, we found weakly positive relationships between HDPs and summer conception and winter delivery.

Burst Spinal Cord Stimulation in Pregnancy: First Clinical Experiences

OBJECTIVES

Spinal cord stimulation (SCS) is a treatment for chronic neuropathic pain. It is based on the delivery of electric impulses to the spinal cord, traditionally in a regular square-wave pattern ("tonic" stimulation) and, more recently, in a rhythmic train-of-five "BurstDR" pattern. The safety of active SCS therapy in pregnancy is not established, and recommendations are based on limited casuistic evidence. We present in this study clinical data on a case series of six women treated with burst SCS during pregnancy. In addition, we present the ultrasonographic flow measurements of fetal and uteroplacental blood flow in a pregnant patient.

MATERIALS AND METHODS

Patients were included if they had been implanted with a full SCS system at Aarhus University Hospital, Denmark, between 2006 and 2020 and received active burst SCS stimulation during a pregnancy. Telephone interviews were conducted, including details on SCS therapy, medication, pregnancy course and outcome, and health status of the offspring. In one patient, the uteroplacental and fetal blood flow was assessed in gestational week 29 by Doppler flow measurements performed during both ON and OFF phases of the SCS system.

RESULTS

Six patients were included with a total of 11 pregnancies. Three pregnancies ended in miscarriages, all in the same patient who had preexisting significant risk factors for miscarriage. Eight resulted in a live-born child with normal birth weight for gestational age; seven were born at term, and one was born late preterm, in gestational week 36. Ultrasonographic Doppler flow, measured in one patient, was normal and did not reveal any immediate changes between burst SCS ON and OFF. Seven children were reported healthy with normal neurodevelopment and one physically healthy but with developmental delays.

CONCLUSIONS

The data presented in this study add to the accumulating evidence of the safety of SCS in pregnancy.

Vitamin D-Related Risk Factors for Maternal Morbidity during Pregnancy: A Systematic Review

Vitamin D has well-defined classical functions related to metabolism and bone health but also has non-classical effects that may influence pregnancy. Maternal morbidity remains a significant health care concern worldwide, despite efforts to improve maternal health. Nutritional deficiencies of vitamin D during pregnancy are related to adverse pregnancy outcomes, but the evidence base is difficult to navigate. The primary purpose of this review is to map the evidence on the effects of deficiencies of vitamin D on pregnancy outcome and the dosage used in such studies. A systematic search was performed for studies on vitamin D status during pregnancy and maternal outcomes. A total of 50 studies came from PubMed, 15 studies came from Cochrane, and 150 studies came from Embase, for a total of 215 articles. After screening, 34 were identified as candidate studies for inclusion. Finally, 28 articles met the inclusion criteria, which originated from 15 countries. The studies included 14 original research studies and 13 review studies conducted between 2012 and 2021. This review was finally limited to the 14 original studies. This systematic review was conducted according to the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, and the quality and strength of the evidence was evaluated using the Navigation Guide Systematic Review Methodology (SING). We found evidence that supports the idea that supplementary vitamin D for pregnant women is important for reducing the risk of gestational diabetes, hypertension, preeclampsia, early labor, and other complications. The data retrieved from this review are consistent with the hypothesis that adequate vitamin D levels might contribute to a healthy pregnancy.

Eye diseases during pregnancy: a study with the medical data warehouse in the eye clinic of the Ludwig-Maximilians-Universität München in Munich in Germany

Objective

To analyze the most common ophthalmologic disorders in pregnant women seen in a hospital in Munich in Germany using a big data analysis system, as well as to compare the results obtained with those from other epidemiological studies that used different data acquisition methods.

Methods

We retrospectively analyzed electronic health records of pregnant women who were seen at the ophthalmology department from 2003 to 2019 at the Ludwig-Maximilians-Universität München hospital. The main complaints that led to ophthalmic consultations during this period were evaluated, and also the variation in intraocular pressure of patients throughout gestational trimesters by analyzing data from the data warehouse system.

Results

A total of 27,326 electronic health records were analyzed. Of participants, 149 (0.54%) required eye care during pregnancy. Their mean intraocular pressure was 17mmHg in the first trimester, 12mmHg in the second trimester, and 14mmHg in the third trimester. The most prevalent findings were dry eye (29.3%) and conjunctivitis (16%), and ametropia (16%). The most common posterior segment problem was diabetic retinopathy (4.6%). The lower mean intraocular pressure in the second and third trimester found in our study is in accordance with other studies that used other method for data acquisition.

Conclusion

The most common ophthalmic conditions found in this study population were dry eye, conjunctivitis, and ametropia. The use of data warehouse proved to be useful for acquiring and analyzing data from many patients. This study results are comparable with other studies in published literature that adopted different methodology.

Antenatal Exposure to UV-B Radiation and Preeclampsia: A Retrospective Cohort Study

Background

Risk of preeclampsia varies by month of delivery. We tested whether this seasonal patterning may be mediated through maternal vitamin D concentration using antenatal exposure to UV‐B radiation as an instrumental variable.

Methods and Results

Scottish maternity records were linked to antenatal UV‐B exposure derived from satellites between 2000 and 2010. Logistic regression analyses were used to explore the association between UV‐B and preeclampsia, adjusting for the potential confounding effects of month of conception, child's sex, gestation, parity, and mean monthly temperature. Of the 522 896 eligible singleton deliveries, 8689 (1.66%) mothers developed preeclampsia. Total antenatal UV‐B exposure ranged from 43.18 to 101.11 kJ/m² and was associated with reduced risk of preeclampsia with evidence of a dose‐response relationship (highest quintile of exposure: adjusted odds ratio, 0.57; 95% CI, 0.44–0.72; P<0.001). Associations were demonstrated for UV‐B exposure in all 3 trimesters.

Conclusions

The seasonal patterning of preeclampsia may be mediated through low maternal vitamin D concentration in winter resulting from low UV‐B radiation. Interventional studies are required to determine whether vitamin D supplements or UV‐B–emitting light boxes can reduce the seasonal patterning of preeclampsia.

Power determination in vitamin D randomised control trials and characterising factors affecting it through a novel simulation-based tool

Thousands of observational studies have linked vitamin D deficiency with numerous diseases, but randomised controlled trials (RCTs) often fail to show benefit of supplementation. Population characteristics and trial design have long been suspected to undermine power but were not systematically investigated. We propose a flexible generative model to characterise benefit of vitamin D supplementation at the individual level, and use this to quantify power in RCTs. The model can account for seasonality and population heterogeneity. In a simulated 1-year trial with 1000 participants per arm and assuming a 25-hydroxyvitamin D (25OHD) increase of 20 nmol/L due to the intervention, with baseline 25OHD in the population of 15, 35, 50, 60 and 75 nmol/L, the power to detect intervention effect was 77%, 99%, 95%, 68% and 19%, respectively. The number of participants required per arm to achieve 80% power according to baseline 25OHD of 15-60 nmol/L was 1200, 400, 600 and 1400, respectively. As expected, larger increases in 25OHD due to supplementation improved power in certain scenarios. For a population baseline of 50 nmol/L, with 1500 participants in each arm, there was 100% power to detect a 20 nmol/L 25OHD increase while it was 76% for a 10 nmol/L increase. Population characteristics and trial design, including temporal considerations, have a dramatic impact on power and required sample size in vitamin D RCTs.

Association between serum beta-human chorionic gonadotropin and inflammation, oxidative stress in pregnancy-induced hypertension

The aberrant increase of circulating beta-human chorionic gonadotropin (β-HCG) at early stages of pregnancy can be used to predict gestational hypertension. However, the association of β-HCG and inflammation, oxidative stress in pregnancy-caused hypertensive disorder on perinatal stage remains unclear. A case-controlled study was performed, with 133 adult pregnant women participated in their perinatal stage. Participants in this research included 45 with mild preeclampsia, 40 with severe preeclampsia and 48 without hypertension. Higher circulating β-HCG level was correlated with severer pregnancy-induced hypertension. Independent contribution of inflammatory factors including interleukin-6, tumor necrosis factor-α and interferon-γ and oxidative stress factors including thiobarbituric acid reactive substance and total antioxidant capacity to severe pregnancy-induced hypertension was significant (P < 0.001). The correlation of circulating β-HCG levels with inflammatory and oxidative stress markers in patients with pregnancy-induced hypertension in perinatal stage was statistically significant.