Cindy Farquhar, Luk Rombauts, Jan Am Kremer, Anne Lethaby, Reuben Olugbenga Ayeleke

Among subfertile women undergoing assisted reproductive technology (ART), hormone pills given before ovarian stimulation may improve outcomes. To determine whether pretreatment with the combined oral contraceptive pill (COCP) or with a progestogen or oestrogen alone in ovarian stimulation protocols affects outcomes in subfertile couples undergoing ART. We searched the following databases from inception to January 2017: Cochrane Gynaecology and Fertility Group Specialised Register, The Cochrane Central Register Studies Online, MEDLINE, Embase, CINAHL and PsycINFO. We also searched the reference lists of relevant articles and registers of ongoing trials. Randomised controlled trials (RCTs) of hormonal pretreatment in women undergoing ART. We used standard methodological procedures recommended by Cochrane. The primary review outcomes were live birth or ongoing pregnancy and pregnancy loss. We included 29 RCTs (4701 women) of pretreatment with COCPs, progestogens or oestrogens versus no pretreatment or alternative pretreatments, in gonadotrophin-releasing hormone (GnRH) agonist or antagonist cycles. Overall, evidence quality ranged from very low to moderate. The main limitations were risk of bias and imprecision. Most studies did not describe their methods in adequate detail. Combined oral contraceptive pill versus no pretreatmentWith antagonist cycles in both groups the rate of live birth or ongoing pregnancy was lower in the pretreatment group (OR 0.74, 95% CI 0.58 to 0.95; 6 RCTs; 1335 women; I(2) = 0%; moderate quality evidence). There was insufficient evidence to determine whether the groups differed in rates of pregnancy loss (OR 1.36, 95% CI 0.82 to 2.26; 5 RCTs; 868 women; I(2) = 0%; moderate quality evidence), multiple pregnancy (OR 2.21, 95% CI 0.53 to 9.26; 2 RCTs; 125 women; I(2) = 0%; low quality evidence), ovarian hyperstimulation syndrome (OHSS; OR 0.98, 95% CI 0.28 to 3.40; 2 RCTs; 642 women; I(2) = 0%, low quality evidence), or ovarian cyst formation (OR 0.47, 95% CI 0.08 to 2.75; 1 RCT; 64 women; very low quality evidence).In COCP plus antagonist cycles versus no pretreatment in agonist cycles, there was insufficient evidence to determine whether the groups differed in rates of live birth or ongoing pregnancy (OR 0.89, 95% CI 0.64 to 1.25; 4 RCTs; 724 women; I(2) = 0%; moderate quality evidence), multiple pregnancy (OR 1.36, 95% CI 0.85 to 2.19; 4 RCTs; 546 women; I(2) = 0%; moderate quality evidence), or OHSS (OR 0.63, 95% CI 0.20 to 1.96; 2 RCTs; 290 women, I(2) = 0%), but there were fewer pregnancy losses in the pretreatment group (OR 0.40, 95% CI 0.22 to 0.72; 5 RCTs; 780 women; I(2) = 0%; moderate quality evidence). There were no data suitable for analysis on ovarian cyst formation.One small study comparing COCP versus no pretreatment in agonist cycles showed no clear difference between the groups for any of the reported outcomes. Progestogen versus no pretreatmentAll studies used the same protocol (antagonist, agonist or gonadotrophins) in both groups. There was insufficient evidence to determine any differences in rates of live birth or ongoing pregnancy (agonist: OR 1.35, 95% CI 0.69 to 2.65; 2 RCTs; 222 women; I(2) = 24%; low quality evidence; antagonist: OR 0.67, 95% CI 0.18 to 2.54; 1 RCT; 47 women; low quality evidence; gonadotrophins: OR 0.63, 95% CI 0.09 to 4.23; 1 RCT; 42 women; very low quality evidence), pregnancy loss (agonist: OR 2.26, 95% CI 0.67 to 7.55; 2 RCTs; 222 women; I(2) = 0%; low quality evidence; antagonist: OR 0.36, 95% CI 0.06 to 2.09; 1 RCT; 47 women; low quality evidence; gonadotrophins: OR 1.00, 95% CI 0.06 to 17.12; 1 RCT; 42 women; very low quality evidence) or multiple pregnancy (agonist: no data available; antagonist: OR 1.05, 95% CI 0.06 to 17.76; 1 RCT; 47 women; low quality evidence; gonadotrophins: no data available). Three studies, all using agonist cycles, reported ovarian cyst formation: rates were lower in the pretreatment group (OR 0.16, 95% CI 0.08 to 0.32; 374 women; I(2) = 1%; moderate quality evidence). There were no data on OHSS. Oestrogen versus no pretreatmentIn antagonist or agonist cycles, there was insufficient evidence to determine whether the groups differed in rates of live birth or ongoing pregnancy (antagonist versus antagonist: OR 0.79, 95% CI 0.53 to 1.17; 2 RCTs; 502 women; I(2) = 0%; low quality evidence; antagonist versus agonist: OR 0.88, 95% CI 0.51 to 1.50; 2 RCTs; 242 women; I(2) = 0%; very low quality evidence), pregnancy loss (antagonist versus antagonist: OR 0.16, 95% CI 0.02 to 1.47; 1 RCT; 49 women; very low quality evidence; antagonist versus agonist: OR 1.59, 95% CI 0.62 to 4.06; 1 RCT; 220 women; very low quality evidence), multiple pregnancy (antagonist versus antagonist: no data available; antagonist versus agonist: OR 2.24, 95% CI 0.09 to 53.59; 1 RCT; 22 women; very low quality evidence) or OHSS (antagonist versus antagonist: no data available; antagonist versus agonist: OR 1.54, 95% CI 0.25 to 9.42; 1 RCT; 220 women). Ovarian cyst formation was not reported. Head-to-head comparisonsCOCP was compared with progestogen (1 RCT, 44 women), and with oestrogen (2 RCTs, 146 women), and progestogen was compared with oestrogen (1 RCT, 48 women), with an antagonist cycle in both groups. COCP in an agonist cycle was compared with oestrogen in an antagonist cycle (1 RCT, 25 women). Data were scant but there was no clear evidence that any of the groups differed in rates of live birth or ongoing pregnancy, pregnancy loss or other adverse events. Among women undergoing ovarian stimulation in antagonist protocols, COCP pretreatment was associated with a lower rate of live birth or ongoing pregnancy than no pretreatment. There was insufficient evidence to determine whether rates of live birth or ongoing pregnancy were influenced by pretreatment with progestogens or oestrogens, or by COCP pretreatment using other stimulation protocols. Findings on adverse events were inconclusive, except that progesterone pretreatment may reduce the risk of ovarian cysts in agonist cycles, and COCP in antagonist cycles may reduce the risk of pregnancy loss compared with no pretreatment in agonist cycles.