MVIIIHealth The MVIII app
← Back

Research · Medication

Letrozole and clomiphene

In women with PCOS, pooled trials found more live births with letrozole than with clomiphene, 27.5% against 19.1% in the largest trial. In unexplained infertility, the two drugs did not differ, and clomiphene did not outdo no treatment. Multiple pregnancy, ovarian hyperstimulation, hot flushes and visual symptoms are recorded harms. Letrozole's label warns of fetal harm.

Add to Bio HackChecked 2026-11-13
Status
Prescription drugs in the US. Clomiphene citrate is FDA-approved to treat ovulatory dysfunction in women who want to become pregnant [1]. Letrozole is FDA-approved for breast cancer in postmenopausal women, so its use to bring on ovulation is off-label, and its label lists pregnancy as a contraindication [2].
Also called
letrozole, Femara, clomiphene, clomiphene citrate, clomifene, Clomid, Milophene, ovulation induction pills, aromatase inhibitor, selective estrogen receptor modulator, SERM, enclomiphene
Taken for
getting pregnant with PCOS, bringing on ovulation, irregular or absent ovulation, unexplained infertility, fertility treatment with insemination (IUI), raising testosterone in men

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help4

Reported risks6

What people take it for, and what was found

Shown to help4

StrongStudied in womenVery common

Live birth in PCOS: letrozole compared with clomiphene

Shown to raise live births in women with PCOS against clomiphene, 27.5% against 19.1% in the largest trial, about one extra birth per 10 women treated.

Compared with clomiphene or other selective estrogen receptor modulators [3]; clomiphene [4][5]

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
Across 11 trials (2,060 women), live births after ovulation induction and timed intercourse were higher with letrozole than with selective estrogen receptor modulators such as clomiphene (OR 1.72, 95% CI 1.40 to 2.11, I² 0%), with a number needed to treat of 10. Where 20% of women would have a live birth on clomiphene, 27% to 35% would on letrozole [3]. A second meta-analysis, with 8 trials reporting live birth, found a risk ratio of 1.49 (95% CI 1.27 to 1.74) [4]. In the PPCOS II trial, 103 of 374 women (27.5%) on letrozole and 72 of 376 (19.1%) on clomiphene had a live birth over up to five cycles (rate ratio 1.44, 95% CI 1.10 to 1.87) [5].
Population
2,060 women with anovulatory PCOS in 11 trials, within a review of 41 trials and 6,522 women [3]. 3,952 women with PCOS in 29 trials [4]. 750 women aged 18 to 40 with PCOS, double-blind, at US centers [5].
Sources
[3], [4], [5]
Caveats
The Cochrane review set aside six earlier trials over concerns about the validity of their data, and a funnel plot showed mild asymmetry suggesting some trials favoring the comparison drugs may be missing [3]. The authors of the second review describe the quality of the evidence as mixed [4].
StrongStudied in womenVery common

Ovulation and pregnancy in PCOS: letrozole compared with clomiphene

Shown to raise ovulation and pregnancy rates in women with PCOS against clomiphene. In the largest trial, 61.7% of letrozole cycles and 48.3% of clomiphene cycles were ovulatory.

Compared with clomiphene [4][5][6]; clomiphene or other selective estrogen receptor modulators [3]

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
Ovulation was more frequent with letrozole across 22 trials (RR 1.14, 95% CI 1.06 to 1.21) [4] and across 50 trials (RR 1.20, 95% CI 1.13 to 1.26), and pregnancy across 50 trials (RR 1.44, 95% CI 1.28 to 1.62). The endometrium was thicker on letrozole (SMD 0.89) and fewer follicles developed (SMD -0.56) [6]. In PPCOS II, 834 of 1,352 letrozole cycles (61.7%) and 688 of 1,425 clomiphene cycles (48.3%) were ovulatory [5]. Clinical pregnancy was higher with letrozole across 23 trials (OR 1.69, 95% CI 1.45 to 1.98): where 24% would conceive on clomiphene, 32% to 39% would on letrozole [3].
Population
Women with PCOS in 22 trials [4] and 50 trials [6]. 750 women with PCOS [5]. 3,321 women in 23 trials [3].
Sources
[3], [4], [5], [6]
Caveats
Heterogeneity was moderate to high in the 50-trial analysis (I² 54% for ovulation, 66% for pregnancy, 98% for endometrial thickness) [6]. Ovulation and pregnancy are steps toward a live birth, which is reported in the block above.
LimitedStudied in women

Pregnancy in PCOS: clomiphene compared with placebo

Limited evidence: clomiphene raised clinical pregnancy against placebo in women with PCOS, in 3 small trials of 133 women. No placebo-controlled trial reported live birth.

Compared with placebo [7]; gonadotropin injections [7]

The numbers and sources
Effect
Clomiphene was linked to more clinical pregnancies than placebo (OR 5.91, 95% CI 1.77 to 19.68). If 5% conceived on placebo, between 8% and 50% would on clomiphene. No live birth, miscarriage, multiple pregnancy or ovarian hyperstimulation data were reported against placebo. Against a gonadotropin, clomiphene was linked to fewer pregnancies, ongoing pregnancies and live births, in limited evidence [7].
Population
133 women in 3 trials, within a review of 28 trials and 3,377 women with anovulatory subfertility [7].
Sources
[7]
Caveats
The reviewers rated the evidence low to very low in quality, mainly for imprecision and poor reporting, and advise caution because of low event rates [7].
ModerateStudied in men

Testosterone in men: clomiphene

Shown to raise total testosterone in men with low testosterone, by about 274 ng/dL against placebo, in pooled trials of clomiphene or enclomiphene.

Compared with placebo [13]; testosterone gel [13]; human chorionic gonadotropin [13]; the same men before treatment [14]

The numbers and sources
Effect
Against placebo, clomiphene or enclomiphene raised total testosterone by 273.76 ng/dL (95% CI 191.87 to 355.66, I² 89%), LH by 4.66 IU/L and FSH by 4.59 IU/L. Total testosterone did not differ from testosterone gel. Levels were higher than with hCG alone [13]. Across 17 studies pooled in a second review, total testosterone rose during treatment (pooled estimate 2.60, 95% CI 1.82 to 3.38, unit not given in the abstract), along with free testosterone, LH, FSH, SHBG and estradiol. Symptom scores on the Androgen Deficiency in Aging Males questionnaire improved. Side effects were reported by fewer than 10% of study populations and no serious adverse events were reported [14].
Population
Men with functional hypogonadism in randomized trials [13]. 1,642 men with hypogonadism in 19 studies, 4 randomized and 15 observational, treated for 1.5 to 52 months [14].
Sources
[13], [14]
Caveats
The first review pooled clomiphene with enclomiphene and heterogeneity was high [13]. The second rests mostly on before-and-after observational studies [14]. Use in men is off-label in the US [1]. Neither abstract reports fractures, heart events or fertility.

Not shown to help3

ModerateStudied in women

Live birth in unexplained infertility: clomiphene compared with no treatment

Not shown to raise live births in women with unexplained infertility against no treatment or placebo. In one trial, 14% on clomiphene and 17% with no treatment had a baby.

Compared with no treatment or placebo [8]; expectant management, meaning no treatment for six months [9]

The numbers and sources
Effect
Clomiphene did not raise live births against no treatment or placebo (OR 0.79, 95% CI 0.45 to 1.38). Clinical pregnancy did not differ with insemination (OR 2.40, 95% CI 0.70 to 8.19), without it (OR 1.03, 95% CI 0.64 to 1.66), or with an hCG trigger (OR 1.66, 95% CI 0.56 to 4.80) [8]. In a Scottish trial, live births were 26 of 192 (14%) with clomiphene, 32 of 193 (17%) with expectant management and 43 of 191 (23%) with unstimulated insemination. Against expectant management, the odds ratio was 0.79 (95% CI 0.45 to 1.38) for clomiphene and 1.46 (95% CI 0.88 to 2.43) for insemination [9].
Population
1,159 women in 7 trials, at clomiphene doses of 50 to 250 mg for up to 10 days [8]. 580 women in couples with over two years of infertility, confirmed ovulation, open tubes and motile sperm, in five Scottish hospitals [9].
Sources
[8], [9]
Caveats
The review's live birth estimate is identical to the Scottish trial's, so it may rest on that one trial. Heterogeneity between trials ranged from 34% to 58% [8].
StrongStudied in women

Unexplained infertility: letrozole compared with clomiphene

Not shown to differ from clomiphene in women with unexplained infertility, in two meta-analyses. One large trial found live birth rates of 18.7% on letrozole and 23.3% on clomiphene.

Compared with clomiphene [10][11][12]; gonadotropin injections [12]

The numbers and sources
Effect
Across 8 trials, a positive pregnancy test occurred in 24% on letrozole and 23% on clomiphene (RR 1.08, 95% CI 0.85 to 1.36). Clinical pregnancy (RR 1.15, 95% CI 0.71 to 1.85) and live birth (RR 0.94, 95% CI 0.83 to 1.08) did not differ [10]. In insemination cycles, total pregnancy did not differ (RR 1.06), and miscarriage was lower with letrozole (RR 0.61) [11]. In the AMIGOS trial of stimulation with insemination for up to four cycles, live birth rates were 32.2% with gonadotropins, 23.3% with clomiphene and 18.7% with letrozole. Letrozole's pregnancy rate was lower than gonadotropins' (P < 0.001) and did not differ significantly from clomiphene's (P = 0.10) [12].
Population
2,647 women with unexplained infertility in 8 trials [10]. Women with unexplained infertility having insemination, in trials the abstract does not count [11]. 900 ovulatory women aged 18 to 40 at US centers [12].
Sources
[10], [11], [12]
Caveats
Heterogeneity between trials was significant (I² 60.8%) [10]. Most of these trials paired the drug with insemination, so they do not test the drug alone.
LimitedStudied in women

PCOS: letrozole compared with ovarian drilling surgery

Limited evidence: in one trial of 141 women with PCOS, live births did not differ significantly between letrozole and laparoscopic ovarian drilling.

Compared with laparoscopic ovarian drilling [3]

The numbers and sources
Effect
Live birth OR 2.07 (95% CI 0.99 to 4.32). Where 22% would have a live birth after drilling, 24% to 47% would on letrozole. Clinical pregnancy did not differ significantly across 3 trials (OR 1.47, 95% CI 0.95 to 2.28) [3].
Population
141 women in 1 trial for live birth, 367 women in 3 trials for pregnancy [3].
Sources
[3]
Caveats
The reviewers rated the live birth evidence very low in certainty and the pregnancy evidence low [3].

Doses studied

The PPCOS II trial started clomiphene at 50 mg a day or letrozole at 2.5 mg a day on cycle days 3 to 7, raising the dose for poor ovulation up to 150 mg of clomiphene or 7.5 mg of letrozole a day, for up to 5 cycles [15]. The clomiphene label lists a starting course of 50 mg a day for 5 days, a second course of 100 mg a day for 5 days for women who do not ovulate, and a total of about six cycles [1]. Trials of clomiphene in unexplained infertility used 50 to 250 mg a day for up to 10 days [8], and trials in PCOS compared 10-day with 5-day courses [7]. The letrozole label dose, for breast cancer, is 2.5 mg once daily [2]. The abstracts of the reviews in men do not give doses [13][14].

Risks

Reported risks5

LimitedStudied in womenVery common

Ovarian enlargement, hot flushes and other common side effects

The clomiphene label lists ovarian enlargement in 13.6% and hot flushes in 10.4% of women in its trials. Against clomiphene, letrozole had fewer hot flushes but more fatigue and dizziness.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
In 8,029 patients in the clomiphene trials, reported adverse events were ovarian enlargement 13.6%, hot flushes 10.4%, abdominal or pelvic discomfort and bloating 5.5%, nausea and vomiting 2.2%, breast discomfort 2.1%, headache 1.3% and abnormal uterine bleeding 1.3% [1]. In PPCOS II, hot flushes were more common on clomiphene, fatigue and dizziness were more common on letrozole, and other adverse events were similar [5].
Population
8,029 women in uncontrolled label trials [1]. 750 women with PCOS [5].
Sources
[1], [5]
Caveats
The label trials had no placebo group, and the label notes 498 patients may have been counted twice [1]. The PPCOS II abstract does not give the rates [5].
ModerateStudied in womenCommon

Multiple pregnancy

The clomiphene label reports 8% of pregnancies in its trials were multiple. Pooled PCOS trials found multiple pregnancy in 2.2% of women on clomiphene and 1.6% on letrozole.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
Of 2,369 pregnancies with known outcome in the clomiphene trials, 7.98% were multiple: 6.9% twins, 0.5% triplets, 0.3% quadruplets and 0.1% quintuplets [1]. In pooled PCOS trials, multiple pregnancy occurred in 2.2% on selective estrogen receptor modulators and 1.6% on letrozole (OR 0.74, 95% CI 0.42 to 1.32) [3]. In PPCOS II, 7.4% of clomiphene pregnancies and 3.4% of letrozole pregnancies were twins, not a significant difference [5]. In AMIGOS, multiple gestations made up 9% of ongoing clomiphene pregnancies, 13% of letrozole pregnancies and 32% of gonadotropin pregnancies. All those on the oral drugs were twins, while gonadotropins produced 24 twin and 10 triplet pregnancies [12]. Twin pregnancy did not differ between letrozole and clomiphene in unexplained infertility (RR 0.81, 95% CI 0.39 to 1.68) [10].
Population
2,369 pregnancies in uncontrolled label trials [1]. 2,247 women in 14 trials [3]. 750 women with PCOS [5]. 900 women with unexplained infertility [12].
Sources
[1], [3], [5], [12], [10]
Caveats
None of these trials had an untreated group, so the rates show how often multiple pregnancy occurred on each drug, not how much each drug raised it.
LimitedCommon

Visual symptoms with clomiphene

The label warns of blurred vision, spots or flashes in 1.5% of trial patients, rising with dose and duration, sometimes prolonged and possibly irreversible.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
Visual symptoms, including blurred vision, lights, floaters, double vision and sensitivity to light, were reported by 1.5% of patients in the clinical trials. The label states these increase with total dose or length of treatment, are usually reversible, and have in some cases been prolonged or possibly irreversible. One patient on 200 mg daily had severe loss of visual acuity by day 10, which returned to normal 3 days after stopping. Postmarketing reports include cataract, optic neuritis, retinal hemorrhage and temporary or prolonged loss of vision [1].
Population
8,029 patients in label trials and postmarketing reports [1].
Sources
[1]
Caveats
No placebo group, and postmarketing reports cannot give a rate or prove cause [1].
ModerateStudied in womenUncommon

Ovarian hyperstimulation syndrome

Pooled PCOS trials found ovarian hyperstimulation syndrome in 0.5% of women on letrozole and 0.5% on clomiphene. The clomiphene label warns it can progress rapidly and notes deaths.

The numbers and sources
How common
Uncommon: between 1 in 1,000 and 1 in 100 people.
Effect
Ovarian hyperstimulation syndrome occurred in 0.5% of women in both arms (risk difference 0.00, 95% CI -0.01 to 0.01, 10 trials, 1,848 women) [3]. Three trials of clomiphene against tamoxifen reported no cases in either group [7]. The label states the syndrome may progress within 24 hours to several days, that severe cases can include fluid in the abdomen and chest, kidney failure and blood clots, and that death from hypovolemic shock, hemoconcentration or thromboembolism has occurred [1].
Population
1,848 women with PCOS in 10 trials [3]. Women in 3 trials [7]. Label clinical and postmarketing reports [1].
Sources
[3], [7], [1]
Caveats
The pooled trials were not large enough to measure rare severe cases precisely.
LimitedHow often is not known

Ovarian cancer and borderline ovarian tumors

Linked to borderline ovarian tumors and, in one cohort, invasive ovarian cancer after fertility drugs including clomiphene, in observational studies the reviewers rated very low in certainty.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
A Cochrane review of 37 observational studies (4,684,724 women) did no meta-analysis. One cohort found a raised rate of invasive ovarian cancer in subfertile women given fertility drugs (HR 1.93, 95% CI 1.18 to 3.18), higher in women who stayed childless after clomiphene (HR 2.49, 95% CI 1.30 to 4.78). For borderline tumors, one cohort found an SIR of 7.47 (95% CI 1.54 to 21.83) after clomiphene on 12 cases, and a case-control study an SIR of 2.5 (95% CI 1.3 to 4.5) on 11 cases [18]. A Cochrane review of clomiphene in unexplained subfertility notes that use for more than 12 cycles has been associated with a threefold rise in ovarian cancer risk [8]. The clomiphene label states epidemiology data suggest prolonged use may raise the risk of a borderline or invasive ovarian tumor [1].
Population
4,684,724 women in 13 case-control and 24 cohort studies [18].
Sources
[18], [8], [1]
Caveats
Infertility itself is a risk factor for ovarian cancer, the number of cancers was very small, and dose and drug type were poorly recorded [18]. No data were sourced on letrozole alone.

Mixed results1

ModerateCommon

Birth defects and the letrozole pregnancy warning

The letrozole label states it can cause fetal harm and contraindicates use in pregnancy. Pooled fertility trials found no rise in birth defects against clomiphene, at very low certainty.

The numbers and sources
How common
Common: between 1 in 100 and 1 in 10 people.
Effect
The letrozole label cites postmarketing reports of miscarriage and birth defects after use during pregnancy, and malformations in rats and rabbits at doses below the human dose, while stating the data are insufficient to give a drug-associated risk. It puts the US background rate of major birth defects at 2% to 4% [2]. Across 20 fertility trials, birth defects did not differ between letrozole and clomiphene (RR 1.69, 95% CI 0.51 to 5.58, very low certainty) [16]. In 911 newborns from Canadian fertility centers, anomalies occurred in 2.4% after letrozole and 4.8% after clomiphene, major ones in 1.2% and 3.0%, and heart anomalies in 0.2% and 1.8% [17]. PPCOS II recorded four major anomalies on letrozole and one on clomiphene (P = 0.65) [5]. AMIGOS found no significant differences in anomalies between letrozole, clomiphene and gonadotropins [12]. The clomiphene label states human data do not suggest a rise above the background rate, while animal studies showed malformations, and it contraindicates use in pregnancy [1].
Population
6,679 patients in 20 trials [16]. 911 newborns [17]. 750 women [5]. 900 women [12].
Sources
[2], [16], [17], [5], [12], [1]
Caveats
The newborn study was retrospective [17]. In fertility use, letrozole is taken on cycle days 3 to 7, before ovulation [15], while the label warning concerns exposure during pregnancy [2]. Trials of a few hundred pregnancies cannot rule out a rise in a rare defect.

Checked, no increase found1

Strong

Miscarriage

Not shown to differ between letrozole and clomiphene. About one pregnancy in four ended in miscarriage on either drug in pooled PCOS trials.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
Miscarriage per pregnancy was 25% on selective estrogen receptor modulators and 24% on letrozole (OR 0.94, 95% CI 0.66 to 1.32, high certainty) [3]. Pregnancy loss did not differ between letrozole and clomiphene across fertility trials (RR 1.17, 95% CI 0.91 to 1.50) [16] or in unexplained infertility (RR 0.92, 95% CI 0.61 to 1.38) [10]. In PPCOS II, 31.8% of letrozole pregnancies and 29.1% of clomiphene pregnancies were lost [5]. The clomiphene label reports a miscarriage rate of 20.4% and a stillbirth rate of 1.0% in its trials [1], and the letrozole label gives a US background miscarriage rate of 15% to 20% of recognized pregnancies [2].
Population
736 pregnancies in 15 trials [3]. 20 trials [16]. 8 trials [10]. 257 pregnancies [5]. 2,369 pregnancies in label trials [1].
Sources
[3], [16], [10], [5], [1], [2]
Caveats
These trials compare the two drugs with each other, so they cannot show whether either changes miscarriage risk against no drug.

Claims tested and not found

  1. That clomiphene raises the chance of a baby in unexplained infertility. Live births did not differ from no treatment or placebo in a Cochrane review (OR 0.79, 95% CI 0.45 to 1.38) [8], and were 14% with clomiphene against 17% with no treatment in a 580-woman trial [9].
  2. That letrozole means fewer twins than clomiphene in unexplained infertility. Multiple gestations were 13% of letrozole pregnancies and 9% of clomiphene pregnancies (P = 0.44) [12], and pooled trials found no difference in twins (RR 0.81, 95% CI 0.39 to 1.68) [10].
  3. That children conceived with letrozole develop differently. Following 185 children to age 3 from two US trials, abnormal developmental screening scores did not differ between letrozole, clomiphene and gonadotropin groups [19].

Related

MetforminInositol

Sources

  1. Clomid (clomiphene citrate) tablets, prescribing information. DailyMed, US National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=2ca373c1-4dba-4126-8616-5c533d606fe5
  2. Femara (letrozole) tablets, prescribing information. DailyMed, US National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=82b77d74-085f-45ac-a7dd-1f5c038bf406
  3. Franik S, Le QK, Kremer JA, Kiesel L, Farquhar C. Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome. Cochrane Database of Systematic Reviews. 2022. https://doi.org/10.1002/14651858.cd010287.pub4
  4. Liu Z, Geng Y, Huang Y, et al. Letrozole Compared With Clomiphene Citrate for Polycystic Ovarian Syndrome: A Systematic Review and Meta-analysis. Obstetrics & Gynecology. 2023. https://doi.org/10.1097/aog.0000000000005070
  5. Legro RS, Brzyski RG, Diamond MP, et al. Letrozole versus clomiphene for infertility in the polycystic ovary syndrome. New England Journal of Medicine. 2014. https://doi.org/10.1056/nejmoa1313517
  6. Abu-Zaid A, Gari A, Sabban H, et al. Comparison of Letrozole and Clomiphene Citrate in Pregnancy Outcomes in Patients with Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis. Reproductive Sciences. 2024. https://doi.org/10.1007/s43032-023-01404-8
  7. Brown J, Farquhar C. Clomiphene and other antioestrogens for ovulation induction in polycystic ovarian syndrome. Cochrane Database of Systematic Reviews. 2016. https://doi.org/10.1002/14651858.cd002249.pub5
  8. Hughes E, Brown J, Collins JJ, Vanderkerchove P. Clomiphene citrate for unexplained subfertility in women. Cochrane Database of Systematic Reviews. 2010. https://doi.org/10.1002/14651858.cd000057.pub2
  9. Bhattacharya S, Harrild K, Mollison J, et al. Clomifene citrate or unstimulated intrauterine insemination compared with expectant management for unexplained infertility: pragmatic randomised controlled trial. BMJ. 2008. https://doi.org/10.1136/bmj.a716
  10. Eskew AM, Bedrick BS, Hardi A, et al. Letrozole Compared With Clomiphene Citrate for Unexplained Infertility: A Systematic Review and Meta-analysis. Obstetrics & Gynecology. 2019. https://doi.org/10.1097/aog.0000000000003105
  11. Qin F, Zhou Y, Huan L, Gui W. Comparison of clomiphene and letrozole for superovulation in patients with unexplained infertility undergoing intrauterine insemination: A systematic review and meta-analysis. Medicine. 2020. https://doi.org/10.1097/md.0000000000021006
  12. Diamond MP, Legro RS, Coutifaris C, et al. Letrozole, Gonadotropin, or Clomiphene for Unexplained Infertility. New England Journal of Medicine. 2015. https://doi.org/10.1056/nejmoa1414827
  13. Hohl A, Chavez MP, Pasqualotto E, et al. Clomiphene or enclomiphene citrate for the treatment of male hypogonadism: a systematic review and meta-analysis of randomized controlled trials. Archives of Endocrinology and Metabolism. 2025. https://doi.org/10.20945/2359-4292-2025-0093
  14. Huijben M, Lock MTWT, de Kemp VF, de Kort LMO, van Breda HMK. Clomiphene citrate for men with hypogonadism: a systematic review and meta-analysis. Andrology. 2022. https://doi.org/10.1111/andr.13146
  15. Legro RS, Kunselman AR, Brzyski RG, et al. The Pregnancy in Polycystic Ovary Syndrome II (PPCOS II) trial: rationale and design of a double-blind randomized trial of clomiphene citrate and letrozole for the treatment of infertility in women with polycystic ovary syndrome. Contemporary Clinical Trials. 2012. https://doi.org/10.1016/j.cct.2011.12.005
  16. Etrusco A, D'Amato A, Agrifoglio V, et al. Does the use of letrozole in infertility treatment increase the risk of foetal malformations? A systematic review and meta-analysis of randomized controlled trials. European Journal of Obstetrics & Gynecology and Reproductive Biology. 2025. https://doi.org/10.1016/j.ejogrb.2025.114531
  17. Tulandi T, Martin J, Al-Fadhli R, et al. Congenital malformations among 911 newborns conceived after infertility treatment with letrozole or clomiphene citrate. Fertility and Sterility. 2006. https://doi.org/10.1016/j.fertnstert.2006.03.014
  18. Rizzuto I, Behrens RF, Smith LA. Risk of ovarian cancer in women treated with ovarian stimulating drugs for infertility. Cochrane Database of Systematic Reviews. 2019. https://doi.org/10.1002/14651858.cd008215.pub3
  19. Legro RS, Diamond MP, Coutifaris C, et al. Pregnancy registry: three-year follow-up of children conceived from letrozole, clomiphene, or gonadotropins. Fertility and Sterility. 2020. https://doi.org/10.1016/j.fertnstert.2019.12.023

Everything in the library