The first observation made in the study was the significant increase in the number of patients with regular menstruations after BS without the impact on the absolute number of menstruation cycles. Most of the similar studies confirm this observation [
5,
6,
13,
16,
17,
19]. Many of the studies analyze the menstruation improvement in the selected population of obese patients with PCOS [
5,
12,
13]. It is a very positive observation that the observed improvement of 35% concerned the whole analyzed population, without the distinction of PCOS patients. In the PCOS patients, the lowering of the BMI has a strong and well-documented association with menstrual pattern improvement [
5]. In obese patients without PCOS, such a relationship is much weaker. Therefore, the high chances of improvement of the regularity of the menstruations, with or without the diagnosis of PCOS, seem to have its place in the counseling before the BS.
We did not observe any significant differences before and after BS in terms of prolonged (> 7 days) menstrual bleeding. The only study obtained by the authors shares similar observations [
6]. The relatively high proportion (12.4%) in comparison with the general population before the surgery seems to possibly be the effect of hyperestrogenism caused by obesity. In our study, unfortunately, the heaviness of menstrual bleeding was not analyzed in order not to create perception bias. It is possible that the reduction of hyperestrogenism caused by excessive weight loss could lead to not only more regular but also less heavy menstruations.
We did not observe any improvement in the clinical manifestations of hyperandrogenism prevalence—acne and hirsutism—before and after BS. Studies analyzing the effects of BS on incidence of these symptoms in the PCOS population showed a significant beneficial effect of BS [
13,
23]. Christ and Falcone compared a group of PCOS and non-PCOS patients after BS and found a higher decline in the androgen levels in the PCOS group. Patients from the PCOS group had higher androgen levels at the baseline, and after BS, their DHEAS and free testosterone levels did not differ from the controls. The decrease in androgen levels after BS is also associated with an increase of sex hormone binding globulin (SHBG). The more significant reduction in androgen level may explain the more beneficial effects on reduction of acne and hirsutism in the PCOS group. However, the study by Legro et al., which analyzed the population without distinction on those with or without PCOS, observed a similar lack of beneficial effects of BS on the clinical manifestation of hyperandrogenism as in our study [
17]. As the average time of questionnaire completion is approximately 3 years after the BS, if such an improvement occurred, it would have been observed. Therefore, it is likely that BS has a most beneficial effect in terms of hyperandrogenism improvement only in patients with PCOS.
The next interesting aspect of this study is the use of different birth control methods in the analyzed group. It has been established that the use of estrogen-based type of contraception in obese patients has a steady negative impact on the thromboembolic event risk [
9]. The UK MEC advises against combined hormonal contraception (CHC) use in women with a body mass index (BMI) ≥ 35 kg/m
2 [
24]. In addition to this, the use of most popular form of CHC, oral contraception, is associated with high risk of suboptimal efficiency, mostly due to malabsorption of medicines administered orally [
11]. The observation made during the study as the approximately 15% of patients both before and after the surgery used CHC seems to be alarming. This proportion, despite being relatively low in comparison with other studies, does not change after BS. Similar observations were made in the USA [
18]. The studies by Ginstman et al. and Luyssen et al. provided different observations, as in their studies, patients after BS used CHC less often [
6,
14]. The fact that such observation was not made leads to a suspicion that BMI was taken into account to a minimal level during contraception counseling in this group of patients. What is more, the majority of analyzed patients used hormonal OC and there were no significant differences in its use before and after surgery. The study of Damhof et al. which classified use of OC after BS as “unsafe” showed significant, nearly 2-fold, reduction of OC after BS [
25]. According to the consensus recommendations by Shawe et al., patients with the history of bariatric surgery require appropriate safe and effective contraception, especially during the rapid weight loss period [
26]. According to the recommendations, absorption of orally administered contraceptives can be compromised and other methods of birth control should be advised [
26]. Although the guidelines discourage use of combined oral contraception (COC) in patients after BS, there is a lack of level 1 evidence on the decreased absorption of oral estrogens after BS. The actual reliability of COC after currently used BS procedure has not been sufficiently analyzed, and guidelines are based on pharmacokinetic studies that analyzed older types of BS like jejunoileal bypass. There are some new studies suggesting normal pharmacokinetics of etonogestrel after BS, and the subject of estrogen and progestagen bioavailability after BS should be subject to further studies [
27]. The problem of optimum postoperative contraceptive methods should be discussed with the patients as pre-operative counseling plays a major role in the postoperative gynecologic care. Mengesha et al. have observed that even one perioperative contraception counseling has a positive effect on adequate contraception use [
28].