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Revisiting optimal hormonal contraception following bariatric surgery
Contraception 87 (2013) 131 – 133
Commentary
Revisiting optimal hormonal contraception following bariatric surgery☆ Zaher O. Merhi⁎ Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Vermont College of Medicine, Burlington, VT 05401, USA Received 27 January 2012; revised 15 June 2012; accepted 21 June 2012
1. Introduction It is estimated that around one third of women of reproductive age in the United States are obese [1]. Weight loss is a major problem for most of these women. Bariatric surgery provides greater and more durable weight reduction than behavioral and pharmacological interventions for morbid obesity, making surgical weight loss alternatives an increasingly common strategy among reproductive-aged women [2]. Gastric banding and gastric bypass are the two most widely used techniques worldwide [3], with bypass surgery being the most commonly performed in the United States [4].
2. The need for reliable contraception post bariatric surgery As surgical weight loss becomes more commonly performed in women of reproductive age [2,5], addressing the need for adequate contraception in post-bariatric-surgery patients is more frequently becoming an issue. Many postoperative care plans routinely utilize contraception to prevent pregnancy during the first 12–18 months following surgery as recommended by the American College of Obstetricians and Gynecologists (ACOG) [5]. This is because the initial months following surgery are associated with rapid weight loss, which could potentially cause
☆
Conflict of interest: none. ⁎ Corresponding author. University of Vermont College of Medicine, Burlington, Vermont 05401, USA. Tel.: +1 802 847 5112; fax: +1 802 847 5626. E-mail address: [email protected]. 0010-7824/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.contraception.2012.06.013
adverse effects on a pregnancy [5], although some data support the fact that many adverse maternal and neonatal outcomes may be lower in women who become pregnant after having had bariatric surgery [6,7]. While there has been concern about decreased effectiveness of hormonal contraceptives among obese women, the evidence is limited and inconsistent [8–16]. Obesity by itself might impair the effectiveness of hormonal contraception [14,17–19]. In clinical trials of the transdermal contraceptive patch, women in the highest weight decile (90 kg or more) had a substantially higher failure rate [19], although compliance did not differ by obesity status [20]. A study by Edelman et al. [17] evaluated the impact of obesity on oral contraceptive pill (OCP) pharmacokinetics. In that cohort study, it was found that, in obese women, levonorgestrel (LNG) had significantly longer half-life and took longer to reach a steady state in the circulation when compared with women of normal weight. There was also a tendency toward greater hypothalamic–pituitary–ovarian axis activity in the obese group. Obese women exhibited higher estradiol levels consistent with more follicular development, and more obese women ovulated [17]. Another case–control study performed in a West Coast health maintenance organization observed a higher risk of OCP failure in obese women than in women with a normal body mass index (BMI) (odds ratio 1.72; 95 % confidence interval: 1.04–2.82) [18]. On the other hand, several reports concluded that obesity does not increase the risk of OCP failure [12,21–23]. Despite the existence of the American Society for Bariatric Surgery since 1983 and an increasing utilization of surgical intervention in the management of obesity, there is, as yet, no level I evidence addressing the effectiveness of hormonal contraceptive in post-bariatric-surgery patients [24]. A practice bulletin (June 2009) by the ACOG reported that “…because there is an increased risk of oral
132
Commentary / Contraception 87 (2013) 131–133
contraception failure after bariatric surgery with a significant malabsorption component, nonoral administration of hormonal contraception should be considered in these patients” [25]. However, this statement was based on level III evidence, did not discriminate between the different types of bariatric surgery (restrictive versus malabsorptive) and was based on limited numbers of women with incomplete follow-up.
3. Limited evidence but concern about OCP effectiveness after bariatric surgical procedures with malabsorption Few small studies have addressed the issue of OCP and bariatric surgery [8,9]. A study by Victor et al. [9] on seven morbidly obese women (mean weight 129 kg preoperatively), aged between 20 and 44 years, who underwent jejunoileal bypass (mean weight loss of 39 kg) showed that plasma steroid levels were lower after the ingestion of 3 mg norethisterone and/or 0.25 mg LNG during the first 8 h after ingestion of the pills as compared to the control group (consisting of five nonobese healthy fertile women with mean weight of 57 kg in each of the norethisterone and levonorgestrel groups). The most probable explanation for the lower levels of hormones after bariatric surgery in this study is that intestinal absorption of steroids was decreased by this relatively aggressive weight loss operation. This finding raises the concern that the risk of OCP failure is increased in patients who undergo malabsorptive procedures. However, in that study, lower plasma levels were not correlated with evidence of contraceptive failure (for instance, by showing breakthrough ovulation), and patients were not followed over time to capture data on pregnancy rates. In another study by Gerrits et al. [8] of 40 women aged between 16 and 44 years, 2 of 9 women (average BMI of 39 preoperatively) developed an unexpected pregnancy in the postoperative period despite the use of the same oral contraceptive before and after biliopancreatic diversion. In that study, women who used double contraception [like OCPs with condoms or OCP with intrauterine device (IUD)] or used other forms of contraception (like injectable contraceptive or IUD alone) before and after the operation did not become pregnant. Although that study included a small number of patients and had a short follow-up, only those two participants who used OCP as the only contraception had a postoperative pregnancy. These findings indicate that OCP alone may not be sufficiently reliable to protect women against unintended pregnancy in the postoperative period, particularly when the procedure involves substantial malabsorption. On the other hand, Andersen et al. [26] evaluated the influence of bypass surgery on the intestinal absorption of D-norgestrel and estradiol. The authors gave women (n= 18) who underwent jejunoileostomy a single dose of micronized
estradiol (4 mg) and D-norgestrel (125 mcg), and they did not find reduced circulating levels of these hormones following the operation when compared to the control group (six nonoperated obese women). That study did not evaluate the clinical outcome of contraceptive effectiveness and did not evaluate the absorption of more commonly used components of OCPs such as LNG or ethinylestradiol. Additionally, the type of bariatric surgery in that study is no longer performed. Options other than OCPs have been studied in the postbariatric-surgery context. Interestingly, Ciangura et al. [27] looked into the effectiveness of the etonogestrel (ENG)releasing implant following bariatric surgery. In that study, they compared the serum concentration of ENG before and 3 and 6 months following Roux-en-Y gastric bypass in three young women (who lost 33.6 kg in 6 months), and they found that ENG levels decreased with weight loss but remained (mean of 170 pg/mL) above the minimum concentration required for effective contraception. That study indicated that the implant might represent an effective contraceptive method until at least 8 months after insertion (which was performed 2 months preoperatively) in women undergoing bariatric surgery. However, studies with larger sample sizes and longer follow-up are needed to assess whether contraceptive effectiveness of the implant is decreased in obese women as compared with normal-weight women. Another study [28] reported that the LNG-releasing IUD is an acceptable option by adolescents undergoing bariatric surgery (23 of 25 women had the LNG-IUD inserted). In that study, the LNG-releasing IUD was effective at least 6 months postoperatively (time of historical followup), although one participant experienced unanticipated expulsion of the IUD and another participant requested IUD removal secondary to uterine bleeding.
4. Future directions There is a critical need to establish a rational plan of action for women who undergo bariatric surgery and require contraception, as the operation raises a number of concerns for women. First, it seems likely, but remains unproven, that pregnancy during the rapid weight loss phase in the first few months following bariatric surgery should be avoided, as it may represent a serious risk to fetal nutrition. If women who undergo weight loss surgery utilize less effective contraception, then the need to avoid pregnancy during this particularly worrisome interval may not be met. Second, there is evidence that obesity is associated with reduced fertility [29,30], and noncontracepting women who assume they will remain infertile postoperatively may experience an unplanned pregnancy if they are using a less effective method. To address these issues, future studies should compare the hormonal profiles of women who are taking OCPs following bariatric surgery to those of obese control women. Obese women have dampened luteinizing hormone (LH) pulses [31] that theoretically will make these
Commentary / Contraception 87 (2013) 131–133
patients easier to suppress by OCP. On the other hand, the work of Edelman et al. [17] showed that the time to reach steady-state levels of LNG after OCP ingestion appears to be twice as long among obese women compared with women of normal weight; therefore, the interval until hypothalamic– pituitary–ovarian activity is suppressed may be lengthened, placing obese women at higher risk for ovulation. As patients lose weight following bariatric surgery, the endogenous LH pulsatility will become more robust with higher LH pulses, and they might become even harder to suppress. With decreased absorption of oral contraceptive steroids post gastric bypass, there is a potential to find real differences in LH pulses despite the ingestion of OCPs. Finally, the majority of women undergoing bariatric surgery are not referred to an obstetrician/gynecologist for contraceptive counseling [32]. Women with a history of bariatric surgery who want to avoid pregnancy need access to a wide range of safe and highly effective methods. While evidence is limited, the theoretical concern about decreased effectiveness in these women should focus on OCP use among women with history of a malabsorptive procedure. Women with restrictive procedures might safely and effectively use OCPs [24], and women with any procedure can safely use any other hormonal method (given no other medical conditions or characteristics that would restrict use). Given the recommendations that women should not become pregnant for at least 12–18 months, long-acting and highly effective contraceptive methods might be particularly appropriate. There is a wide opportunity for clinicians to improve counseling and increase the use of an adequate contraception in this understudied population. Health care coordination between gynecologists and bariatric surgeons is crucial to ensure that women with history of bariatric surgery have comprehensive counseling and access to all methods of contraception.
References [1] Flegal KM, Carroll MD, Kit BK, Ogden CL. Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999–2010. JAMA 2012;307:491-7. [2] Santry HP, Gillen DL, Lauderdale DS. Trends in bariatric surgical procedures. JAMA 2005;294:1909-17. [3] Buchwald H. Consensus conference statement bariatric surgery for morbid obesity: health implications for patients, health professionals, and third-party payers. Surg Obes Relat Dis 2005;1:371-81. [4] Tice JA, Karliner L, Walsh J, Petersen AJ, Feldman MD. Gastric banding or bypass? A systematic review comparing the two most popular bariatric procedures. Am J Med 2008;121:885-93. [5] ACOG Committee. Opinion number 315, September 2005. Obesity in pregnancy. Obstet Gynecol 2005;106:671-5. [6] Maggard MA, Yermilov I, Li Z, et al. Pregnancy and fertility following bariatric surgery: a systematic review. JAMA 2008;300:2286-96. [7] Colquitt J, Clegg A, Loveman E, Royle P, Sidhu MK. Surgery for morbid obesity. Cochrane Database Syst Rev 2005:CD003641. [8] Gerrits EG, Ceulemans R, van Hee R, Hendrickx L, Totte E. Contraceptive treatment after biliopancreatic diversion needs consensus. Obes Surg 2003;13:378-82.
133
[9] Victor A, Odlind V, Kral JG. Oral contraceptive absorption and sex hormone binding globulins in obese women: effects of jejunoileal bypass. Gastroenterol Clin North Am 1987;16:483-91. [10] Trussell J, Schwarz EB, Guthrie K. Obesity and oral contraceptive pill failure. Contraception 2009;79:334-8. [11] Kripke C. Lower- vs higher-dose estrogen for contraception. Am Fam Physician 2005;72:1224-5. [12] Brunner LR, Hogue CJ. The role of body weight in oral contraceptive failure: results from the 1995 national survey of family growth. Ann Epidemiol 2005;15:492-9. [13] Merhi ZO. Challenging oral contraception after weight loss by bariatric surgery. Gynecol Obstet Invest 2007;64:100-2. [14] Holt VL, Cushing-Haugen KL, Daling JR. Body weight and risk of oral contraceptive failure. Obstet Gynecol 2002;99:820-7. [15] Paulen ME, Zapata LB, Cansino C, Curtis KM, Jamieson DJ. Contraceptive use among women with a history of bariatric surgery: a systematic review. Contraception 2010;82:86-94. [16] Lopez LM, Grimes DA, Chen-Mok M, Westhoff C, Edelman A, Helmerhorst FM. Hormonal contraceptives for contraception in overweight or obese women. Cochrane Database Syst Rev 2010: CD008452. [17] Edelman AB, Carlson NE, Cherala G, Munar MY, Stouffer RL, Cameron JL, et al. Impact of obesity on oral contraceptive pharmacokinetics and hypothalamic–pituitary–ovarian activity. Contraception 2009;80:119-27. [18] Holt VL, Scholes D, Wicklund KG, Cushing-Haugen KL, Daling JR. Body mass index, weight, and oral contraceptive failure risk. Obstet Gynecol 2005;105:46-52. [19] Zieman M, Guillebaud J, Weisberg E, Shangold GA, Fisher AC, Creasy GW. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system: the analysis of pooled data. Fertil Steril 2002;77:S13-8. [20] Huber LR, Hogue CJ, Stein AD, et al. Contraceptive use and discontinuation: findings from the contraceptive history, initiation, and choice study. Am J Obstet Gynecol 2006;194:1290-5. [21] Brunner Huber LR, Hogue CJ, Stein AD, Drews C, Zieman M. Body mass index and risk for oral contraceptive failure: a case-cohort study in South Carolina. Ann Epidemiol 2006;16:637-43. [22] Westhoff CL, Torgal AH, Mayeda ER, Pike MC, Stanczyk FZ. Pharmacokinetics of a combined oral contraceptive in obese and normal-weight women. Contraception 2010;81:474-80. [23] Westhoff CL, Hait HI, Reape KZ. Body weight does not impact pregnancy rates during use of a low-dose extended-regimen 91-day oral contraceptive. Contraception 2012;85:235-9. [24] U S. medical eligibility criteria for contraceptive use, 2010. MMWR Recomm Rep 2010;59:1-86. [25] ACOG practice bulletin no. 105: bariatric surgery and pregnancy. Obstet Gynecol 2009;113:1405-13. [26] Andersen AN, Lebech PE, Sorensen TI, Borggaard B. Sex hormone levels and intestinal absorption of estradiol and D-norgestrel in women following bypass surgery for morbid obesity. Int J Obes 1982;6:91-6. [27] Ciangura C, Corigliano N, Basdevant A, et al. Etonorgestrel concentrations in morbidly obese women following Roux-en-Y gastric bypass surgery: three case reports. Contraception 2011;84:649-51. [28] Hillman JB, Miller RJ, Inge TH. Menstrual concerns and intrauterine contraception among adolescent bariatric surgery patients. J Womens Health (Larchmt) 2011;20:533-8. [29] Esinler I, Bozdag G, Yarali H. Impact of isolated obesity on ICSI outcome. Reprod Biomed Online 2008;17:583-7. [30] Obesity and reproduction an educational bulletin. Fertil Steril 2008; 90:S21-9. [31] Jain A, Polotsky AJ, Rochester D, et al. Pulsatile luteinizing hormone amplitude and progesterone metabolite excretion are reduced in obese women. J Clin Endocrinol Metab 2007;92:2468-73. [32] Mody SK, Hacker MR, Dodge LE, Thornton K, Schneider B, Haider S. Contraceptive counseling for women who undergo bariatric surgery. J Womens Health (Larchmt) 2011;20:1785-8.
Commentary
Revisiting optimal hormonal contraception following bariatric surgery☆ Zaher O. Merhi⁎ Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Vermont College of Medicine, Burlington, VT 05401, USA Received 27 January 2012; revised 15 June 2012; accepted 21 June 2012
1. Introduction It is estimated that around one third of women of reproductive age in the United States are obese [1]. Weight loss is a major problem for most of these women. Bariatric surgery provides greater and more durable weight reduction than behavioral and pharmacological interventions for morbid obesity, making surgical weight loss alternatives an increasingly common strategy among reproductive-aged women [2]. Gastric banding and gastric bypass are the two most widely used techniques worldwide [3], with bypass surgery being the most commonly performed in the United States [4].
2. The need for reliable contraception post bariatric surgery As surgical weight loss becomes more commonly performed in women of reproductive age [2,5], addressing the need for adequate contraception in post-bariatric-surgery patients is more frequently becoming an issue. Many postoperative care plans routinely utilize contraception to prevent pregnancy during the first 12–18 months following surgery as recommended by the American College of Obstetricians and Gynecologists (ACOG) [5]. This is because the initial months following surgery are associated with rapid weight loss, which could potentially cause
☆
Conflict of interest: none. ⁎ Corresponding author. University of Vermont College of Medicine, Burlington, Vermont 05401, USA. Tel.: +1 802 847 5112; fax: +1 802 847 5626. E-mail address: [email protected]. 0010-7824/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.contraception.2012.06.013
adverse effects on a pregnancy [5], although some data support the fact that many adverse maternal and neonatal outcomes may be lower in women who become pregnant after having had bariatric surgery [6,7]. While there has been concern about decreased effectiveness of hormonal contraceptives among obese women, the evidence is limited and inconsistent [8–16]. Obesity by itself might impair the effectiveness of hormonal contraception [14,17–19]. In clinical trials of the transdermal contraceptive patch, women in the highest weight decile (90 kg or more) had a substantially higher failure rate [19], although compliance did not differ by obesity status [20]. A study by Edelman et al. [17] evaluated the impact of obesity on oral contraceptive pill (OCP) pharmacokinetics. In that cohort study, it was found that, in obese women, levonorgestrel (LNG) had significantly longer half-life and took longer to reach a steady state in the circulation when compared with women of normal weight. There was also a tendency toward greater hypothalamic–pituitary–ovarian axis activity in the obese group. Obese women exhibited higher estradiol levels consistent with more follicular development, and more obese women ovulated [17]. Another case–control study performed in a West Coast health maintenance organization observed a higher risk of OCP failure in obese women than in women with a normal body mass index (BMI) (odds ratio 1.72; 95 % confidence interval: 1.04–2.82) [18]. On the other hand, several reports concluded that obesity does not increase the risk of OCP failure [12,21–23]. Despite the existence of the American Society for Bariatric Surgery since 1983 and an increasing utilization of surgical intervention in the management of obesity, there is, as yet, no level I evidence addressing the effectiveness of hormonal contraceptive in post-bariatric-surgery patients [24]. A practice bulletin (June 2009) by the ACOG reported that “…because there is an increased risk of oral
132
Commentary / Contraception 87 (2013) 131–133
contraception failure after bariatric surgery with a significant malabsorption component, nonoral administration of hormonal contraception should be considered in these patients” [25]. However, this statement was based on level III evidence, did not discriminate between the different types of bariatric surgery (restrictive versus malabsorptive) and was based on limited numbers of women with incomplete follow-up.
3. Limited evidence but concern about OCP effectiveness after bariatric surgical procedures with malabsorption Few small studies have addressed the issue of OCP and bariatric surgery [8,9]. A study by Victor et al. [9] on seven morbidly obese women (mean weight 129 kg preoperatively), aged between 20 and 44 years, who underwent jejunoileal bypass (mean weight loss of 39 kg) showed that plasma steroid levels were lower after the ingestion of 3 mg norethisterone and/or 0.25 mg LNG during the first 8 h after ingestion of the pills as compared to the control group (consisting of five nonobese healthy fertile women with mean weight of 57 kg in each of the norethisterone and levonorgestrel groups). The most probable explanation for the lower levels of hormones after bariatric surgery in this study is that intestinal absorption of steroids was decreased by this relatively aggressive weight loss operation. This finding raises the concern that the risk of OCP failure is increased in patients who undergo malabsorptive procedures. However, in that study, lower plasma levels were not correlated with evidence of contraceptive failure (for instance, by showing breakthrough ovulation), and patients were not followed over time to capture data on pregnancy rates. In another study by Gerrits et al. [8] of 40 women aged between 16 and 44 years, 2 of 9 women (average BMI of 39 preoperatively) developed an unexpected pregnancy in the postoperative period despite the use of the same oral contraceptive before and after biliopancreatic diversion. In that study, women who used double contraception [like OCPs with condoms or OCP with intrauterine device (IUD)] or used other forms of contraception (like injectable contraceptive or IUD alone) before and after the operation did not become pregnant. Although that study included a small number of patients and had a short follow-up, only those two participants who used OCP as the only contraception had a postoperative pregnancy. These findings indicate that OCP alone may not be sufficiently reliable to protect women against unintended pregnancy in the postoperative period, particularly when the procedure involves substantial malabsorption. On the other hand, Andersen et al. [26] evaluated the influence of bypass surgery on the intestinal absorption of D-norgestrel and estradiol. The authors gave women (n= 18) who underwent jejunoileostomy a single dose of micronized
estradiol (4 mg) and D-norgestrel (125 mcg), and they did not find reduced circulating levels of these hormones following the operation when compared to the control group (six nonoperated obese women). That study did not evaluate the clinical outcome of contraceptive effectiveness and did not evaluate the absorption of more commonly used components of OCPs such as LNG or ethinylestradiol. Additionally, the type of bariatric surgery in that study is no longer performed. Options other than OCPs have been studied in the postbariatric-surgery context. Interestingly, Ciangura et al. [27] looked into the effectiveness of the etonogestrel (ENG)releasing implant following bariatric surgery. In that study, they compared the serum concentration of ENG before and 3 and 6 months following Roux-en-Y gastric bypass in three young women (who lost 33.6 kg in 6 months), and they found that ENG levels decreased with weight loss but remained (mean of 170 pg/mL) above the minimum concentration required for effective contraception. That study indicated that the implant might represent an effective contraceptive method until at least 8 months after insertion (which was performed 2 months preoperatively) in women undergoing bariatric surgery. However, studies with larger sample sizes and longer follow-up are needed to assess whether contraceptive effectiveness of the implant is decreased in obese women as compared with normal-weight women. Another study [28] reported that the LNG-releasing IUD is an acceptable option by adolescents undergoing bariatric surgery (23 of 25 women had the LNG-IUD inserted). In that study, the LNG-releasing IUD was effective at least 6 months postoperatively (time of historical followup), although one participant experienced unanticipated expulsion of the IUD and another participant requested IUD removal secondary to uterine bleeding.
4. Future directions There is a critical need to establish a rational plan of action for women who undergo bariatric surgery and require contraception, as the operation raises a number of concerns for women. First, it seems likely, but remains unproven, that pregnancy during the rapid weight loss phase in the first few months following bariatric surgery should be avoided, as it may represent a serious risk to fetal nutrition. If women who undergo weight loss surgery utilize less effective contraception, then the need to avoid pregnancy during this particularly worrisome interval may not be met. Second, there is evidence that obesity is associated with reduced fertility [29,30], and noncontracepting women who assume they will remain infertile postoperatively may experience an unplanned pregnancy if they are using a less effective method. To address these issues, future studies should compare the hormonal profiles of women who are taking OCPs following bariatric surgery to those of obese control women. Obese women have dampened luteinizing hormone (LH) pulses [31] that theoretically will make these
Commentary / Contraception 87 (2013) 131–133
patients easier to suppress by OCP. On the other hand, the work of Edelman et al. [17] showed that the time to reach steady-state levels of LNG after OCP ingestion appears to be twice as long among obese women compared with women of normal weight; therefore, the interval until hypothalamic– pituitary–ovarian activity is suppressed may be lengthened, placing obese women at higher risk for ovulation. As patients lose weight following bariatric surgery, the endogenous LH pulsatility will become more robust with higher LH pulses, and they might become even harder to suppress. With decreased absorption of oral contraceptive steroids post gastric bypass, there is a potential to find real differences in LH pulses despite the ingestion of OCPs. Finally, the majority of women undergoing bariatric surgery are not referred to an obstetrician/gynecologist for contraceptive counseling [32]. Women with a history of bariatric surgery who want to avoid pregnancy need access to a wide range of safe and highly effective methods. While evidence is limited, the theoretical concern about decreased effectiveness in these women should focus on OCP use among women with history of a malabsorptive procedure. Women with restrictive procedures might safely and effectively use OCPs [24], and women with any procedure can safely use any other hormonal method (given no other medical conditions or characteristics that would restrict use). Given the recommendations that women should not become pregnant for at least 12–18 months, long-acting and highly effective contraceptive methods might be particularly appropriate. There is a wide opportunity for clinicians to improve counseling and increase the use of an adequate contraception in this understudied population. Health care coordination between gynecologists and bariatric surgeons is crucial to ensure that women with history of bariatric surgery have comprehensive counseling and access to all methods of contraception.
References [1] Flegal KM, Carroll MD, Kit BK, Ogden CL. Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999–2010. JAMA 2012;307:491-7. [2] Santry HP, Gillen DL, Lauderdale DS. Trends in bariatric surgical procedures. JAMA 2005;294:1909-17. [3] Buchwald H. Consensus conference statement bariatric surgery for morbid obesity: health implications for patients, health professionals, and third-party payers. Surg Obes Relat Dis 2005;1:371-81. [4] Tice JA, Karliner L, Walsh J, Petersen AJ, Feldman MD. Gastric banding or bypass? A systematic review comparing the two most popular bariatric procedures. Am J Med 2008;121:885-93. [5] ACOG Committee. Opinion number 315, September 2005. Obesity in pregnancy. Obstet Gynecol 2005;106:671-5. [6] Maggard MA, Yermilov I, Li Z, et al. Pregnancy and fertility following bariatric surgery: a systematic review. JAMA 2008;300:2286-96. [7] Colquitt J, Clegg A, Loveman E, Royle P, Sidhu MK. Surgery for morbid obesity. Cochrane Database Syst Rev 2005:CD003641. [8] Gerrits EG, Ceulemans R, van Hee R, Hendrickx L, Totte E. Contraceptive treatment after biliopancreatic diversion needs consensus. Obes Surg 2003;13:378-82.
133
[9] Victor A, Odlind V, Kral JG. Oral contraceptive absorption and sex hormone binding globulins in obese women: effects of jejunoileal bypass. Gastroenterol Clin North Am 1987;16:483-91. [10] Trussell J, Schwarz EB, Guthrie K. Obesity and oral contraceptive pill failure. Contraception 2009;79:334-8. [11] Kripke C. Lower- vs higher-dose estrogen for contraception. Am Fam Physician 2005;72:1224-5. [12] Brunner LR, Hogue CJ. The role of body weight in oral contraceptive failure: results from the 1995 national survey of family growth. Ann Epidemiol 2005;15:492-9. [13] Merhi ZO. Challenging oral contraception after weight loss by bariatric surgery. Gynecol Obstet Invest 2007;64:100-2. [14] Holt VL, Cushing-Haugen KL, Daling JR. Body weight and risk of oral contraceptive failure. Obstet Gynecol 2002;99:820-7. [15] Paulen ME, Zapata LB, Cansino C, Curtis KM, Jamieson DJ. Contraceptive use among women with a history of bariatric surgery: a systematic review. Contraception 2010;82:86-94. [16] Lopez LM, Grimes DA, Chen-Mok M, Westhoff C, Edelman A, Helmerhorst FM. Hormonal contraceptives for contraception in overweight or obese women. Cochrane Database Syst Rev 2010: CD008452. [17] Edelman AB, Carlson NE, Cherala G, Munar MY, Stouffer RL, Cameron JL, et al. Impact of obesity on oral contraceptive pharmacokinetics and hypothalamic–pituitary–ovarian activity. Contraception 2009;80:119-27. [18] Holt VL, Scholes D, Wicklund KG, Cushing-Haugen KL, Daling JR. Body mass index, weight, and oral contraceptive failure risk. Obstet Gynecol 2005;105:46-52. [19] Zieman M, Guillebaud J, Weisberg E, Shangold GA, Fisher AC, Creasy GW. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system: the analysis of pooled data. Fertil Steril 2002;77:S13-8. [20] Huber LR, Hogue CJ, Stein AD, et al. Contraceptive use and discontinuation: findings from the contraceptive history, initiation, and choice study. Am J Obstet Gynecol 2006;194:1290-5. [21] Brunner Huber LR, Hogue CJ, Stein AD, Drews C, Zieman M. Body mass index and risk for oral contraceptive failure: a case-cohort study in South Carolina. Ann Epidemiol 2006;16:637-43. [22] Westhoff CL, Torgal AH, Mayeda ER, Pike MC, Stanczyk FZ. Pharmacokinetics of a combined oral contraceptive in obese and normal-weight women. Contraception 2010;81:474-80. [23] Westhoff CL, Hait HI, Reape KZ. Body weight does not impact pregnancy rates during use of a low-dose extended-regimen 91-day oral contraceptive. Contraception 2012;85:235-9. [24] U S. medical eligibility criteria for contraceptive use, 2010. MMWR Recomm Rep 2010;59:1-86. [25] ACOG practice bulletin no. 105: bariatric surgery and pregnancy. Obstet Gynecol 2009;113:1405-13. [26] Andersen AN, Lebech PE, Sorensen TI, Borggaard B. Sex hormone levels and intestinal absorption of estradiol and D-norgestrel in women following bypass surgery for morbid obesity. Int J Obes 1982;6:91-6. [27] Ciangura C, Corigliano N, Basdevant A, et al. Etonorgestrel concentrations in morbidly obese women following Roux-en-Y gastric bypass surgery: three case reports. Contraception 2011;84:649-51. [28] Hillman JB, Miller RJ, Inge TH. Menstrual concerns and intrauterine contraception among adolescent bariatric surgery patients. J Womens Health (Larchmt) 2011;20:533-8. [29] Esinler I, Bozdag G, Yarali H. Impact of isolated obesity on ICSI outcome. Reprod Biomed Online 2008;17:583-7. [30] Obesity and reproduction an educational bulletin. Fertil Steril 2008; 90:S21-9. [31] Jain A, Polotsky AJ, Rochester D, et al. Pulsatile luteinizing hormone amplitude and progesterone metabolite excretion are reduced in obese women. J Clin Endocrinol Metab 2007;92:2468-73. [32] Mody SK, Hacker MR, Dodge LE, Thornton K, Schneider B, Haider S. Contraceptive counseling for women who undergo bariatric surgery. J Womens Health (Larchmt) 2011;20:1785-8.