Calcium levels during the initiation of labor

Intravenous Calcium to Decrease Blood Loss During Intrapartum Cesarean Delivery: A Randomized Controlled Trial

OBJECTIVE

To evaluate whether prophylactic administration of 1 g of intravenous calcium chloride after cord clamping reduces blood loss from uterine atony during intrapartum cesarean delivery.

METHODS

This single-center, block-randomized, placebo-controlled, double-blind superiority trial compared the effects of 1 g intravenous calcium chloride with those of saline placebo control on blood loss at cesarean delivery. Parturients at 34 or more weeks of gestation requiring intrapartum cesarean delivery after oxytocin exposure in labor were enrolled. Calcium or saline placebo was infused over 10 minutes beginning 1 minute after umbilical cord clamping in addition to standard care with oxytocin. The primary outcome was quantitative blood loss, analyzed by inverse Gaussian regression. Planned subgroup analysis excluded nonatonic bleeding, such as hysterotomy extension, arterial bleeding, and occult placenta accreta. We planned to enroll 120 patients to show a 200-mL reduction in quantitative blood loss in planned subgroup analysis, assuming up to 40% incidence of nonatonic bleeding (80% power, α<0.05).

RESULTS

From April 2022 through March 2023, 828 laboring parturients provided consent and 120 participants were enrolled. Median blood loss was 840 mL in patients allocated to calcium chloride (n=60) and 1,051 mL in patients allocated to placebo (n=60), which was not statistically different (mean reduction 211 mL, 95% CI -33 to 410). In the planned subgroup analysis (n=39 calcium and n=40 placebo), excluding cases of surgeon-documented nonatonic bleeding, calcium reduced quantitative blood loss by 356 mL (95% CI 159-515). Rates of reported side effects were similar between the two groups (38% calcium vs 42% placebo).

CONCLUSION

Prophylactic intravenous calcium chloride administered during intrapartum cesarean delivery after umbilical cord clamping did not significantly reduce blood loss in the primary analysis. However, in the planned subgroup analysis, calcium infusion significantly reduced blood loss by approximately 350 mL. These data suggest that this inexpensive and shelf-stable medication warrants future study as a novel treatment strategy to decrease postpartum hemorrhage, the leading global cause of maternal morbidity and mortality.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov , NCT05027048.

Mode of delivery and maternal vitamin D deficiency: an optimized intelligent Bayesian network algorithm analysis of a stratified randomized controlled field trial

This study aimed to elucidate the algorithm of various influential factors relating to the association between 25-hydroxyvitamin D (25(OH)D) concentration at delivery and mode of delivery. The investigation constituted a secondary analysis using data collected as part of the Khuzestan Vitamin D Deficiency Screening Program in Pregnancy, which is a stratified randomized vitamin D supplementation-controlled trial comprising 1649 eligible pregnant women. The Bayesian Network (BN) method was utilized to determine the association algorithm between diverse influential factors associated with maternal vitamin D and mode of delivery. The optimized intelligent BN algorithm revealed that women presenting with moderate (35.67%; 95% CI: 33.36-37.96) and severe vitamin D deficiency (47.22%; 95% CI: 44.81-49.63) at delivery were more likely to undergo cesarean section than those presenting with normal concentrations of this nutritional hormone (18.62%; 95% CI: 16.74-20.5). The occurrence probabilities of preeclampsia in mothers with normal, moderate, and severe vitamin D deficiency at delivery were (1.5%; 95% CI: 0.92-2.09), (14.01%; 95% CI: 12.33-15.68), and (26.81%; 95% CI: 24.67-28.95), respectively. Additionally, mothers with moderate (11.81%; 95% CI: 10.25-13.36) and severe (27.86%; 95% CI: 25.69-30.02) vitamin D deficiency exhibited a higher probability of preterm delivery in comparison to those presenting with normal concentrations (1.12%; 95% CI: 0.62-1.63). This study demonstrated that the vitamin D status of pregnant women at delivery could directly affect the mode of delivery and indirectly through maternal complications, such as preeclampsia and preterm delivery, leading to a higher occurrence probability of cesarean section.

Time Course Analysis of Transcriptome in Human Myometrium Depending on Labor Duration and Correlating With Postpartum Blood Loss

The maintenance of coordinated powerful episodic contractions of the uterus is the crucial factor for normal labor. The uterine contractility is gradually enhanced with the progression of labor, which is related to the gene expression of the myometrium. Competing endogenous RNA (ceRNA) can also regulate the gene expression. To better understand the role of ceRNA network in labor, transcriptome sequencing was performed on the myometrium of 17 parturients at different labor durations (0–24 h). From this, expression levels of mRNA, long non-coding RNA (lncRNA), circular RNA (circRNA), and microRNA (miRNA) were correlated with labor duration. Then, targeting relationships between mRNAs, lncRNAs, circRNAs, and miRNAs were predicted, and the ceRNA regulatory network was established. The mRNA expression patterns associated with cervical dilation and postpartum bleeding were further investigated. This analysis identified 932 RNAs positively correlated with labor duration (859 mRNAs, 28 lncRNAs, and 45 circRNAs) and 153 RNAs negatively correlated with labor duration (122 mRNAs, 28 lncRNAs, and 3 miRNAs). These mRNAs were involved in protein metabolism, transport, and cytoskeleton functions. According to the targeting relationship among these ceRNAs and mRNAs, a ceRNA network consisting of 3 miRNAs, 72 mRNAs, 2 circRNAs, and 1 lncRNA was established. In addition, two mRNA expression patterns were established using time-series analysis of mRNA expression in different phases of cervical dilation. A ceRNA network analysis for blood loss was performed; postpartum bleeding was closely related to inflammatory response, angiogenesis, and hemostasis. This study identified human myometrial transcriptome and established the ceRNA regulatory network depending on labor duration and highlighted the dynamic changes that occur at ceRNAs during parturition, which need to be considered more in the future to better understand how changes in gene expression are relevant to functional changes in human myometrium at labor.

Calcium chloride for the prevention of uterine atony during cesarean delivery: A pilot randomized controlled trial and pharmacokinetic study

STUDY OBJECTIVE

To assess the feasibility, patient tolerance, pharmacokinetics, and potential effectiveness of a randomized controlled trial protocol investigating intravenous calcium chloride for the prevention of uterine atony during cesarean delivery.

DESIGN

Double-blind, randomized controlled pilot trial with nested population pharmacokinetic analysis.

SETTING

This study was performed at Lucile Packard Children's Hospital, from August 2018 to September 2019.

PATIENTS

Forty patients with at least two risk factors for uterine atony at the time of cesarean delivery.

INTERVENTIONS

One gram of intravenous calcium chloride (n = 20 patients) or a saline placebo control (n = 20 patients), in addition to standard care with oxytocin, upon umbilical cord clamping.

MEASUREMENTS

The primary efficacy-related outcome was the presence of uterine atony defined as the use of a second-line uterotonic medication, surgical interventions for atony, or hemorrhage with blood loss >1000 mL. Blood loss, uterine tone numerical rating scores, serial venous blood calcium levels, hemodynamics, and potential side effects were also assessed.

MAIN RESULTS

The study protocol proved feasible. The incidence of atony was 20% in parturients who received calcium compared to 50% in the placebo group (relative risk 0.38, P = 0.07, 95% CI 0.15-1.07, NNT 3.3). Calcium recipients tolerated the drug infusion well, with no adverse events and an equal incidence of potential side effects in the calcium and placebo groups. Ionized calcium concentration rose significantly in all patients who received calcium infusion, from baseline 1.18 mmol/L to peak levels 1.50-1.60 mmol/L. One-compartment population pharmacokinetics established clearance of 0.93 (95% CI 0.63-1.52) L/min and volume of distribution 76 (95% CI 49-94) L.

CONCLUSIONS

In this pilot study, investigators found that intravenous calcium chloride was well-tolerated by the 20 patients assigned to receive the study drug and may be effective in prevention of uterine atony. A 1-g dose was sufficient to substantially increase calcium levels without any critically elevated lab values or concern for adverse side effects. These encouraging findings warrant further investigation of calcium as a novel agent to prevent uterine atony with an adequately powered clinical trial. Clinical trial registry NCT03867383 https://clinicaltrials.gov/ct2/show/NCT03867383.

Vitamin D and the risk of dystocia: A case-control study

BACKGROUND

Dystocia is one of the most common causes of cesarean section in nulliparous women. Studies have described the presence of vitamin D receptors in the myometrium, but it is still unclear whether vitamin D affects the contractility of the smooth muscles. We therefore aimed to determine the association between the vitamin D serum level at labor and the risk of dystocia.

METHOD

We conducted a case-control study between January 2012 and June 2017. Cases were primiparous women, with spontaneous onset of labor, who gave birth by cesarean section due to dystocia. Controls were primiparous women with a spontaneous vaginal delivery. We included 60 women (30 cases and 30 controls) in the analysis. The differences between cases and controls were assessed using chi-squared test for categorical variables and two-sample t-test or unequal t-test for continuous variables, as appropriate, after evaluation of whether they followed the normal distributions.

RESULTS

The mean serum 25-hydroxyvitamin D concentrations were 53.1nmol/l (95%CI; 45.2 to 60.9) among cases and 69.9nmol/l (95%CI; 57.5 to 82.4) among controls (P = 0.02). The mean plasma parathyroid hormone levels were 2.25 pmol/l and 2.38, respectively (P = 0.57). Even though 78% of all women reported taking a minimum of 10μg/day of vitamin D throughout pregnancy, 43% had vitamin D insufficiency, defined as serum 25-hydroxyvitamin D levels below 50nmol/l.

CONCLUSIONS

In a Danish group of women having a cesarean section due to dystocia, we found decreased vitamin D levels.

A Case Control Study to Evaluate the Association between Primary Cesarean Section for Dystocia and Vitamin D Deficiency

BACKGROUND

Milder forms of vitamin D deficiency could be responsible for poor muscular performance causing dysfunctional labor. The aim of our research was to study the association between vitamin D deficiency and primary cesarean section.

MATERIALS AND METHODS

This was a case control study. Forty six women who delivered by primary cesarean section with dystocia as primary or secondary indication after 37 weeks of gestation were taken as cases and a similar number of women who delivered vaginally were taken as controls. Vitamin D deficiency was diagnosed when the serum 25(OH)D level was ≤20 ng/ml and this was compared between cases and controls.

RESULTS

Median serum (OH) vitamin D levels was 23.3ng/ml among women who delivered by cesarean section and 26.2ng/ml among controls (p=0.196). Baseline characteristics were similar in both groups except for a strong association between Body Mass Index (BMI) and cesarean section, (29.7kg/m(2) in cases and 25.9kg/m(2) in controls p=0.001) seen in multivariate analysis. Vitamin D deficiency was seen in 34.8% of cases and 21.7% of controls (p=0.165).

CONCLUSION

This small case control study did not show a significant association between vitamin D deficiency and primary cesarean section.

Calcium plus vitamin D supplementation affects pregnancy outcomes in gestational diabetes: randomized, double-blind, placebo-controlled trial

OBJECTIVE

The present study was designed to assess the effects of Ca+vitamin D supplementation on pregnancy outcomes in women with gestational diabetes mellitus (GDM).

DESIGN

A randomized, double-blind, placebo-controlled trial was conducted among sixty women with GDM. Participants were divided into two groups to receive Ca+vitamin D supplements or placebo. Individuals in the Ca+vitamin D group (n 30) received 1000 mg Ca/d and two pearls containing 1250 µg (50 000 IU) of cholecalciferol (vitamin D(3)) during the intervention (one at study baseline and another at day 21 of the intervention); those in the placebo group (n 30) received two placebos of vitamin D at the mentioned times and placebos of Ca every day for 6 weeks. Pregnancy outcomes were determined.

SETTING

A urban community setting in Arak, Iran.

SUBJECTS

Sixty women with GDM and their newborns, living in Arak, Iran were enrolled.

RESULTS

Women treated with Ca+vitamin D had a significant decrease in caesarean section rate (23·3 % v. 63·3 %, P=0·002) and maternal hospitalization (0 v. 13·3 %, P=0·03) compared with those receiving placebo. In addition, newborns of GDM women randomized to Ca+vitamin D had no case of macrosomia, while the prevalence of macrosomia among those randomized to placebo was 13·3 % (P=0·03). Lower rates of hyperbilirubinaemia (20·0 % v. 56·7 %, P=0·03) and hospitalization (20·0 % v. 56·7 %, P=0·03) were also seen in the supplemented group of newborns than in the placebo group.

CONCLUSIONS

Ca+vitamin D supplementation for 6 weeks among pregnant women with GDM led to decreased caesarean section rate and maternal hospitalization, and decreased macrosomia, hyperbilirubinaemia and hospitalization in newborns.

Associations of maternal circulating 25-hydroxyvitamin D3 concentration with pregnancy and birth outcomes

OBJECTIVE

To investigate the association of maternal circulating 25-hydroxyvitamin D3 [25(OH)D3] concentration with pregnancy and birth outcomes.

DESIGN

Prospective cohort study.

SETTING

Four geographical areas of Spain, 2003-2008.

POPULATION

Of 2382 mother-child pairs participating in the INfancia y Medio Ambiente (INMA) Project.

METHODS

Maternal circulating 25(OH)D3 concentration was measured in pregnancy (mean [SD] 13.5 [2.2] weeks of gestation). We tested associations of maternal 25(OH)D3 concentration with pregnancy and birth outcomes.

MAIN OUTCOME MEASURES

Gestational diabetes mellitus (GDM), preterm delivery, caesarean section, fetal growth restriction (FGR) and small-for-gestational age (SGA), anthropometric birth outcomes including weight, length and head circumference (HC).

RESULTS

Overall, 31.8% and 19.7% of women had vitamin D insufficiency [25(OH)D3 20-29.99 ng/ml] and deficiency [25(OH)D3 < 20 ng/ml], respectively. After adjustment, there was no association between maternal 25(OH)D3 concentration and risk of GDM or preterm delivery. Women with sufficient vitamin D [25(OH)D3 ≥ 30 ng/ml] had a decreased risk of caesarean section by obstructed labour compared with women with vitamin D deficiency [relative risk (RR) = 0.60, 95% CI 0.37, 0.97). Offspring of mothers with higher circulating 25(OH)D3 concentration tended to have smaller HC [coefficient (SE) per doubling concentration of 25(OH)D3, -0.10 (0.05), P = 0.038]. No significant associations were found for other birth outcomes.

CONCLUSION

This study did not find any evidence of an association between vitamin D status in pregnancy and GDM, preterm delivery, FGR, SGA and anthropometric birth outcomes. Results suggest that sufficient circulating vitamin D concentration [25(OH)D3 ≥ 30 ng/ml] in pregnancy may reduce the risk of caesarean section by obstructed labour.

Seasonal variation of dystocia in a large Danish cohort

Background

Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR) has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population.

Method

We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time.

Results

No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44); instrumental vaginal delivery due to dystocia (p = 0.69); oxytocin augmentation due to dystocia (p = 0.46); and overall dystocia (p = 0.91).

Conclusion

No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.

The effect of DASH diet on pregnancy outcomes in gestational diabetes: a randomized controlled clinical trial

BACKGROUND/OBJECTIVES

The current study was performed to investigate the effects of the Dietary Approaches to Stop Hypertension (DASH) eating plan on pregnancy outcomes in pregnant women with gestational diabetes mellitus (GDM).

SUBJECTS/METHODS

This randomized controlled clinical trial was performed among 52 women diagnosed with GDM. Participants were randomly assigned to consume either the control (n=26) or the DASH diet (n=26) for 4 weeks. The control diet was designed to contain 45-55% carbohydrates, 15-20% protein and 25-30% total fat. The DASH diet was rich in fruits, vegetables, whole grains and low-fat dairy products, and contained lower amounts of saturated fats, cholesterol and refined grains with a total of 2400 mg/day sodium. The numbers of women who commenced insulin therapy after dietary intervention, the mode of delivery and prevalence of polyhydramnios were assessed. The length, weight and head circumference of infants were measured during the first 24 h after birth.

RESULTS

Whereas 46.2% of women in the DASH diet needed to have a cesarean section, this percentage for the control group was 80.8% (P=0.01). The percentage of those who needed to commence insulin therapy after intervention was also significantly different between the two groups (23% for DASH vs 73% for control group, P<0.0001). Infants born to mothers on the DASH diet had significantly lower weight (3222.7 vs 3818.8 g, P<0.0001), head circumference (34.2 vs 35.1 cm, P=0.01) and ponderal index (2.50 vs 2.87 kg/m(3), P<0.0001) compared with those born to mothers on the control diet.

CONCLUSIONS

In conclusion, consumption of DASH diet for 4 weeks among pregnant women with GDM resulted in improved pregnancy outcomes.

High prevalence of hypovitaminosis D in pregnant Japanese women with threatened premature delivery

Serum 25-hydroxyvitamin D (25-OHD) concentrations are thought to accurately reflect vitamin D stores, and vitamin D deficiency causes secondary hyperparathyroidism, irreversible bone loss, and increased risk of fracture. Recent studies suggest that decrease of serum 25-OHD level in mothers could increase the risk of preeclampsia, cesarean section, and craniotabes. Furthermore, this deficiency may affect bone mass and the incidence of neuromuscular diseases of their children in the future. In the present study, the serum concentration of 25-OHD in 93 pregnant women after the 30th week of their gestation was determined by direct radioimmunoassay. Mean 25-OHD levels in spring, summer, fall, and winter were 14.3 ± 5.1, 15.7 ± 6.4, 13.7 ± 5.1, and 13.9 ± 4.2 ng/ml, respectively. Severe vitamin D deficiency (25-OHD < 10 ng/ml) was found in 10 of these 93 women. Overall, hypovitaminosis D, which was defined as serum 25-OHD concentration equal to or less than 20 ng/ml, was revealed in 85 mothers (89.5%). Serum 25-OHD levels were not associated with either intact parathyroid hormone or corrected calcium concentrations, but were negatively associated with serum type I collagen N-terminal telopeptide and bone-specific alkaline phosphatase in these subjects. Mothers with threatened premature delivery had significantly lower 25-OHD levels (11.2 ± 3.2 ng/ml) than those in mothers with normal delivery (15.6 ± 5.1 ng/ml). In conclusion, the present data suggest a high prevalence of hypovitaminosis D in perinatal pregnant Japanese women throughout the year, which seems to affect bone metabolism and to be associated with threatened premature delivery.

Association between vitamin D deficiency and primary cesarean section

BACKGROUND

At the turn of the 20th century, women commonly died in childbirth due to rachitic pelvis. Although rickets virtually disappeared with the discovery of the hormone vitamin D, recent reports suggest vitamin D deficiency is widespread in industrialized nations. Poor muscular performance is an established symptom of vitamin D deficiency. The current U.S. cesarean birth rate is at an all-time high of 30.2%. We analyzed the relationship between maternal serum 25-hydroxyvitamin D [25(OH)D] status, and prevalence of primary cesarean section.

METHODS

Between 2005 and 2007, we measured maternal and infant serum 25(OH)D at birth and abstracted demographic and medical data from the maternal medical record at an urban teaching hospital (Boston, MA) with 2500 births per year. We enrolled 253 women, of whom 43 (17%) had a primary cesarean.

RESULTS

There was an inverse association with having a cesarean section and serum 25(OH)D levels. We found that 28% of women with serum 25(OH)D less than 37.5 nmol/liter had a cesarean section, compared with only 14% of women with 25(OH)D 37.5nmol/liter or greater (P = 0.012). In multivariable logistic regression analysis controlling for race, age, education level, insurance status, and alcohol use, women with 25(OH)D less than 37.5 nmol/liter were almost 4 times as likely to have a cesarean than women with 25(OH)D 37.5 nmol/liter or greater (adjusted odds ratio 3.84; 95% confidence interval 1.71 to 8.62).

CONCLUSION

Vitamin D deficiency was associated with increased odds of primary cesarean section.

Normal Labor: Mechanism and Duration

Labor is refers to the chain of physiologic events that allows a fetus to undertake its journey from the uterus to the outside world. The mean duration of a singleton preganancy is 40.0 weeks (280 days), which is dated from the first day of the last normal menstrual period. The period from 37.0 weeks (259 days) to 42.0 weeks (294 days) of gestation is regarded as "term". This article focuses on the onset progress, and mechanics of normal labor term. Topics such as preterm labor (labor before 37 weeks), postterm labor (labor after 42 weeks), and abnormal labor and delivery have not been addressed and are discussed in detail elsewhere in this issue.