Vitamin C and premature rupture of chorioamniotic membranes

Plasma vitamin C levels and risk of preterm prelabour rupture of membranes

PURPOSE

Preterm prelabour rupture of membranes (PPROM) is a leading cause of preterm births. Its attendant contribution to maternal and perinatal morbidity and mortality makes it imperative to identify factors that may help prevent this condition. This study examined the association between plasma vitamin C concentration and the risk of (PPROM) amongst pregnant women in a tertiary hospital setting.

METHODS

This was a prospective cross sectional study conducted at the Obstetric and Gynaecology Department of University of Benin Teaching Hospital (UBTH), Benin City. The study was in two phases, first a pilot study to determine baseline plasma vitamin C concentration amongst pregnant women in UBTH was conducted. In the main study 80 pregnant women were recruited into two groups of those with PPROM (40 cases) and those without PPROM (40 controls) matched for gestational age. Plasma vitamin C concentration was determined for all study participants and their sociodemographic characters were used to generate a database for analysis.

RESULTS

In the pilot study, plasma vitamin C concentration decreased with increasing gestational age of pregnancy. In the main study plasma vitamin C concentration was significantly lower in women with PPROM than controls without PPROM, 0.53 ± 0.05 vs. 0.58 ± 0.05 mg/dl; P = 0.0001. Both groups (case and control) were comparably matched in age, parity and social class. There was a significant association between low vitamin C levels and the occurrence of PPROM (95% CI 1.53-11.88; P = 0.008).

CONCLUSION

Plasma vitamin C was found to be lower in women with PPROM. Low plasma vitamin C concentration may thus be an associated risk factor for PPROM. Hence improved dietary or drug supplements may be a useful adjunctive strategy to reducing the incidence of PPROM and its attendant adverse sequelae. While this intervention is advocated, further multicentre investigation of the effects of vitamin C on risk of preterm PROM is suggested.

Prevention of PPROM: Current and future strategies

Our understanding of the pathophysiologic processes leading to preterm premature rupture of membranes (PPROM) has grown tremendously in recent years. Evidence suggests that there may be a genetic susceptibility to PPROM and that genetic and environmental elements are important cofactors in its development. A number of risk-based protocols have been proposed in an attempt to identify those women at highest risk for PPROM. While we have made advances in the area of predicting PPROM, treatments based on current risk-based systems have failed to distinguish a specific, effective preventive therapy for PPROM. The concept that genetic factors increase susceptibility or decrease resistance to disease has stimulated new work in the field of PPROM. Several maternal and fetal gene polymorphisms have been identified that are associated with an increased risk for PPROM. Patients with 'susceptible' genotypes may also have clinical risk factors for PPROM resulting in a synergistic increase in the risk for PPROM, a so-called gene-environment interaction. The concept that these gene-environment interactions represent new targets for our efforts to prevent PPROM is explored.

Vitamin C supplementation to prevent premature rupture of the chorioamniotic membranes: a randomized trial

BACKGROUND

Vitamin C is involved in the synthesis and degradation of collagen and is important for maintenance of the chorioamniotic membranes. Inadequate availability of ascorbic acid during pregnancy has been proposed as a risk factor for premature rupture of the chorioamniotic membranes (PROM).

OBJECTIVE

The objective of the study was to evaluate the effectiveness of 100 mg vitamin C/d in preventing PROM.

DESIGN

A controlled double-blind trial was performed. Pregnant women (n = 126) in their 20th wk of gestation were invited; 120 accepted and were randomly assigned to 2 groups (100 mg vitamin C/d or placebo). Every 4 wk, plasma and leukocyte vitamin C concentrations were measured, and each subject was evaluated for cervicovaginal infection. The incidence of PROM was recorded for each group as an indicator of the protective effect of vitamin C supplementation.

RESULTS

One hundred nine patients finished the study. Mean plasma vitamin C concentrations decreased significantly throughout the pregnancy in both groups (P = 0.001), and there were no significant differences between groups. Between weeks 20 and 36, mean leukocyte vitamin C concentrations decreased from 17.5 to 15.23 microg/10(8) cells in the placebo group and increased from 17.26 to 22.17 microg/10(8) cells in the supplemented group (within- and between-group differences: P = 0.001). The incidence of PROM was 14 per 57 pregnancies (24.5%) in the placebo group and 4 per 52 pregnancies (7.69%) in the supplemented group (relative risk: 0.26; 95% CI: 0.078, 0.837).

CONCLUSION

Daily supplementation with 100 mg vitamin C after 20 wk of gestation effectively lessens the incidence of PROM.

Possible interplay between vitamin C deficiency and prolactin in pregnant women with premature rupture of membranes: facts and hypothesis

The precise etiologic mechanisms involved in the premature rupture of membranes (PROM) during pregnancy, the main cause of preterm delivery worldwide, are unknown. Previous studies have shown that: (a) the rupture of chorioamniotic membranes is related to an imbalance between synthesis and degradation of collagen induced by the overexpression/activity of various matrix metalloproteinases (MMP); (b) during human labor and delivery the expression of prolactin receptors (PRL-R) increases in chorioamniotic membranes, decidua and placenta; (c) prolactin (PRL) can influence the synthesis of prostaglandins, the expression of some MMP (MMP-2, MMP-9 and decysin) and tissue inhibitors of MMP in general; (d) vitamin C deficiency induces the expression/activity of extracellular MMP and is considered a risk factor for PROM; and (e) vitamin C potentiates the dopamine-mediated inhibition of PRL in rats. The present hypothesis proposes that a decreased hypothalamic dopaminergic tone-and thus an increased synthesis/release of pituitary PRL - is induced by vitamin C deficiency below a critical threshold (<18 microg/10(8) leukocytes) and that both factors, in turn, would cause upregulation of the expression/activity of several MMP. The increased PRL concentrations (acting like a Th1-type cytokine) along with the overexpression of other proinflammatory cytokines would induce a premature switch from a favorable Th2-type immune response to a noxious Th1-type immune response in the intrauterine environment. This change, in conjunction with the upregulation of MMP-2 and MMP-9, would cause a premature imbalance between synthesis/degradation of collagen in chorioamniotic membranes (an "anticipation" of the normal parturition cascade?), which favors extracellular matrix degradation, proposed as the most relevant event in the genesis of PROM. This hypothesis represents a new dimension in the study of the etiology of PROM.

Collagen synthesis during pregnancy, vitamin C availability, and risk of premature rupture of fetal membranes

OBJECTIVE

To examine the relationship between plasma and leukocyte concentration of ascorbic acid and collagen type I propeptide C during pregnancy and subsequent premature rupture of membranes (PROM).

METHODS

Fifteen women with PROM and 26 controls were compared for plasma and leukocyte concentration of vitamin C and for Pro-C during pregnancy.

RESULTS

A statistically significant difference in maternal leukocyte ascorbic acid concentration was found between the two groups at week 28 of gestation (P50 was 16.90 for PROM group vs. 21.46 for control group; P>0.05). Increased risk for PROM (odds ratio, 10.99; 95% confidence interval, 2.40-49.91) was found with elevated concentrations of Pro-C at week 16 of gestation.

CONCLUSIONS

A higher rate of collagen synthesis early in pregnancy was demonstrated in PROM cases. However, no correlation with ascorbic acid availability was found. This study supports the findings of others that collagen metabolism disturbances are associated with PROM.

The impact of prenatal maternal stress and optimistic disposition on birth outcomes in medically high-risk women

A sizable body of evidence indicates that prenatal maternal stress (PNMS) has an adverse impact on birth outcomes, including birth weight and gestational age at delivery. The authors hypothesized that effects of PNMS are attributable in part to dispositions such as pessimism that lead women to view their lives as stressful and that effects of PNMS and disposition on birth outcome are mediated by prenatal health behaviors. Using structural equations modeling procedures, the authors examined prospective impact of PNMS and dispositional optimism on birth weight and gestational age in a medically high-risk sample (N = 129), controlling for effects of risk and ethnicity. After its strong inverse association with optimism was accounted for, PNMS had no impact on birth outcomes. Women who were least optimistic delivered infants who weighed significantly less, controlling for gestational age. Optimists were more likely to exercise, and exercise was associated with lower risk of preterm delivery. Results suggest that chronic stress in pregnancy may be a reflection of underlying dispositions that contribute to adverse birth outcomes.