Pharmacokinetics of the newer progestogens and the controversy about gestodene

The influence of the menstrual cycle and hormonal contraceptives on cardiorespiratory fitness in physically active women: A systematic review and meta-analysis

Objective

To systematically review and summarize the existing evidence related to the influence of the menstrual cycle (MC) and hormonal contraceptive (HC) use on V˙O_2max in physically active women.

Methods

This systematic review and meta-analysis conforms to the PRISMA statement guidelines. Four (sub-)meta-analyses were performed. Two focused on longitudinal studies examining the same women several times to compare the V˙O_2max during the different menstrual phases or oral contraceptive (OC) use and withdrawal. Two meta-analyses examined if there is a difference in V˙O_2max between OC users and normally menstruating women by analyzing cross-sectional studies assigning physically active women to one of these two groups as well as intervention-based studies (cross-over studies, randomized controlled trials considering only the data of the intervention group) comparing women intra-individually with and without OCs.

Results

Nine of the included studies (107 women) evaluated the influence of the MC, five studies (69 women) the impact of OCs on V˙O_2max, and six studies investigated both topics (88 women). A mean difference of V˙O_2max -0.03 ml/kg/min (95%CI -1.06 to 1.01) between the early follicular and luteal menstrual phase was observed. Between the active and inactive phases of OCs, a mean difference of -0.11 ml/kg/min (95%CI -2.32 to 2.10) was found. The inter-individual comparison of naturally menstruating women and OC users showed a mean difference in V˙O_2max of 0.23 ml/kg/min (95% CI -2.33 to 2.79) in favor of OC use. The intra-individual comparison of the same women showed a mean decrease in V˙O_2max of -0.84 ml/kg/min (95% CI -2.38 to 0.70) after a new start with OCs.

Conclusions

Our meta-analyses showed no effects of the MC or the OCs on V˙O_2max. More high-quality studies are needed determining the MC phases more precisely, including OCs with the current standard formulations and comparing the influence of different progestins.

Birth control pills and nonprofessional voice: acoustic analyses

PURPOSE

Two studies are presented here. Study 1 was aimed at evaluating whether the voice characteristics of women who use birth control pills that contain different progestins differ from the voice characteristics of a control group. Study 2 presents a meta-analysis that combined the results of Study 1 with those from 3 recent studies that compared voices of women who use and do not use birth control pills.

METHOD

In Study 1, voice samples from 30 women with no history of voice training, who use pills with different progestins (drospirenone, desogestrel, gestodene), and 10 women who do not use the pill were recorded at specific time points across the menstrual cycle and were analyzed acoustically. In Study 2, results from Study 1 were analyzed jointly with results from three recent studies, which used similar methodologies.

RESULTS

Results of Study 1 did not reveal acoustic differences in sustained phonation of vowels across the pill groups and controls. Results of the meta-analysis performed in Study 2 indicated that pill users exhibited lower jitter and shimmer values on sustained vowels, whereas no difference of fundamental frequency was observed among women who use the pill.

CONCLUSIONS

These results support findings from previous studies, which suggested that no adverse effect on voice was detected among nonprofessional speakers who use new-generation monophasic birth control pills, for the measures studied. Furthermore, results of the meta-analysis suggested that some acoustic properties of the voice, which are reflected in perturbation measures in sustained vowels, may be improved among women who use the pill.