Does oral carbohydrate supplementation improve labour outcome? A systematic review and individual patient data meta-analysis.

BACKGROUND: Labour is a period of significant physical activity. The importance of carbohydrate intake to improve outcome has been recognised in sports medicine and general surgery. OBJECTIVES: To assess the effect of oral carbohydrate supplementation on labour outcomes. SEARCH STRATEGY: MEDLINE (1966-2014), Embase, the Cochrane Library and clinical trial registries. SELECTION CRITERIA: Randomised controlled trials (RCT) of women randomised to receive oral carbohydrate in labour (<6 cm dilated), versus placebo or standard care. DATA COLLECTION AND ANALYSIS: Authors were contacted to provide data. Individual patient data meta-analyses were performed to calculate pooled risk ratios (RR) and 95% confidence intervals (CI). MAIN RESULTS: Eight RCTs met the inclusion criteria. Six authors responded, four supplied data (n = 691). Three studies used isotonic drinks (one placebo-controlled, two compared with standard care), and one an advice booklet regarding carbohydrate intake. The mean difference in energy intake between the intervention and control groups was small [three studies, 195 kilocalories (kcal), 95% CI 118-273]. There was no difference in the risk of caesarean section (RR 1.15, 95% CI 0.83- 1.61), instrumental birth (RR 1.26, 95% CI 0.96-1.66) or syntocinon augmentation (RR 0.99, 95% CI 0.86-1.13). Length of labour was similar (mean difference -3.15 minutes, 95% CI -35.14 to 41.95). Restricting the analysis to primigravid women did not affect the result. Oral carbohydrates did not increase the risk of vomiting (RR 1.09, 95% CI 0.78-1.52) or 1-minute Apgar score <7 (RR 1.23, 95% CI 0.82-1.83). AUTHORS' CONCLUSION: Oral carbohydrate supplements in small quantities did not alter labour outcome. TWEETABLE ABSTRACT: Oral carbohydrate does not affect labour. But the difference between intervention and control equals 10 teaspoons sugar.

No effect of energy supply during childbirth on delivery outcomes in nulliparous women: a randomised, double-blind, placebo-controlled trial.

The effect of providing oral energy supplements of energy on duration of labour and labour outcomes remains to be clarified. The purpose of this study was to examine whether extra energy supply beyond a self-regulated dietary intake during labour would shorten duration of labour in nulliparous women. A total of 213 healthy women at gestational age >36 weeks received either 1 litre of isotonic energy-drink (n = 111) or placebo-drink (n = 102) at the start of labour. A total of 61% in the intervention group gave birth within the hospital median of 9 hours, compared with 58% in the placebo group (p = 0.68). The mean (SD) durations of labour were 528 (240) minutes and 506 (233) minutes in the intervention and placebo group (p = 0.50), respectively. Extra oral supply of 1 litre energy drink beyond self-regulated intake of food and drink to healthy nulliparous women in birth does not affect the duration of labour.

Training in pregnant women: effects on fetal development and birth.

OBJECTIVE: The effects of high- and medium-intensity exercise on the fetus and on the onset and length of labor, birth weight, and Apgar score were studied in healthy athletes who performed a high level of exercise before conception. STUDY DESIGN: Forty-two women were recruited to the study by newspaper ads and through acquaintances. They elected to follow either a high- or a medium-intensity exercise program throughout pregnancy until 6 weeks after delivery. Documentation of their intensity of activity before conception (retrospectively), during pregnancy, and after delivery was obtained. RESULTS: There were no differences between the high- and medium-intensity exercise group in duration of labor, birth weight, or 1- and 5-minute Apgar scores. The higher level of exercise correlated with a significantly greater maternal weight gain during pregnancy and significantly earlier onset of labor for those women who gave birth to girls but not for those who gave birth to boys. CONCLUSION: Our results indicate that healthy and well-conditioned women may take part in exercise during pregnancy without compromising fetal growth and development as judged by birth weight or complicating the course of pregnancy or labor.

Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis.

The effect of repeated ingestions of fructose, sucrose, and various amounts of glucose on muscle glycogen synthesis during the first 6 h after exhaustive bicycle exercise was studied. Muscle biopsies for glycogen determination were taken before and after exercise, and every second hour during recovery. Blood samples for plasma glucose and insulin determination were taken before and after exercise, and every hour during recovery. When 0.35 (low glucose: N = 5), 0.70 (medium glucose: N = 5), or 1.40 (high glucose: N = 5) g.kg-1 body weight of glucose were given orally at 0, 2, and 4 h after exercise, the rates of glycogen synthesis were (mean +/- SE) 2.1 +/- 0.5, 5.8 +/- 1.0, and 5.7 +/- 0.9 mmol.kg-1.h-1, respectively. When 0.70 g.kg-1 body weight of sucrose (medium sucrose: N = 5), or fructose (medium fructose: N = 7) was ingested accordingly, the rates were 6.2 +/- 0.5 and 3.2 +/- 0.7 mmol.kg-1.h-1. Average plasma glucose level during recovery were similar in low glucose, medium glucose, and high glucose groups (5.76 +/- 0.24, 6.31 +/- 0.64, and 6.52 +/- 0.24 mM), while average plasma insulin levels were higher with higher glucose intake (16 +/- 1, 21 +/- 3, and 38 +/- 4 microU.ml-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Intramuscular fluid pressure during isometric contraction of human skeletal muscle.

Intramuscular fluid pressures were recorded in the vastus medialis of seven healthy male volunteers. Pressures were measured simultaneously at three different sites in the muscle by a catheter-tip transducer with extremely low volume-displacement characteristics and by two extracorporeal transducers connected to slit catheters. All three recording systems gave qualitatively similar results provided the catheters had inner diameters exceeding 0.53 mm and allowed measurement of pressures lasting as short as 1 s. Wick catheters yielded slower responses than slit catheters. At any position intramuscular fluid pressure increased linearly with force up to maximal voluntary contraction (MVC). However, slopes of these curves varied greatly mainly because the pressure was also a linear function of the distance from the fascia. The highest recorded pressure was 570 Torr. At prolonged submaximal contractions intramuscular fluid pressure oscillated independent of contraction force. The linearity of both the pressure-force relationship and the pressure-depth relationship is compatible with a simple model based on the law of Laplace because the muscle fibers are curved during contraction in this muscle. It is hypothesized that blood flow is first compromised deep in the muscle where pressure is highest and in general at lower stress or tension in short bulging muscles with great curvature of the fibers compared with long slender ones.