What do systematic reviews say?

Letrozole vs laparoscopic ovarian drilling

It is very uncertain whether letrozole changes multiple pregnancy rate compared with laparoscopic ovarian drilling (very low certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 3 [0.12, 74.9]
  1 study · 141 participants
  Very low

Letrozole vs laparoscopic ovarian drilling

It is very uncertain whether letrozole changes live birth rate compared with laparoscopic ovarian drilling (very low certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 2.07 [0.99, 4.32]
  1 study · 141 participants
  Very low

Letrozole vs laparoscopic ovarian drilling

The review found no eligible studies for this question.

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  no estimate extracted
  Studies not reported
  No studies found

Letrozole vs laparoscopic ovarian drilling

Letrozole showed no clear difference in clinical pregnancy rate compared with laparoscopic ovarian drilling (low certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 1.47 [0.95, 2.28]
  3 studies · 376 participants
  Low

Letrozole vs laparoscopic ovarian drilling

Letrozole showed no clear difference in miscarriage rate per pregnancy compared with laparoscopic ovarian drilling (low certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 0.65 [0.22, 1.92]
  3 studies · 122 participants
  Low

Letrozole with or without adjuncts vs SERMs with or without adjuncts followed by timed intercourse

Letrozole with or without adjuncts leads to higher live birth rate compared with SERMs with or without adjuncts followed by timed intercourse (high certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 1.72 [1.4, 2.11]
  11 studies · 2060 participants
  High

Letrozole with or without adjuncts vs SERMs with or without adjuncts followed by timed intercourse

Letrozole with or without adjuncts showed no clear difference in ovarian hyperstimulation syndrome rate compared with SERMs with or without adjuncts followed by timed intercourse (high certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  no estimate extracted
  10 studies · 1848 participants
  High

Letrozole with or without adjuncts vs SERMs with or without adjuncts followed by timed intercourse

Letrozole with or without adjuncts leads to higher clinical pregnancy rate compared with SERMs with or without adjuncts followed by timed intercourse (high certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 1.69 [1.45, 1.98]
  23 studies · 3321 participants
  High

Letrozole with or without adjuncts vs SERMs with or without adjuncts followed by timed intercourse

Letrozole with or without adjuncts showed no clear difference in miscarriage rate per pregnancy compared with SERMs with or without adjuncts followed by timed intercourse (high certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 0.94 [0.66, 1.32]
  15 studies · 736 participants
  High

Letrozole with or without adjuncts vs SERMs with or without adjuncts followed by timed intercourse

Letrozole with or without adjuncts showed no clear difference in multiple pregnancy rate compared with SERMs with or without adjuncts followed by timed intercourse (high certainty).

• Aromatase inhibitors (letrozole) for ovulation induction in infertile women with polycystic ovary syndrome 2022 · Cochrane Headline outcomes only
  OR 0.74 [0.42, 1.32]
  14 studies · 2247 participants
  High

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

Clomiphene citrate or letrozole with or without gonadotropins (with… showed no clear difference in live birth per woman compared with gonadotropins (with GnRH agonists or midcycle antagonist) (low certainty).

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  RR 0.92 [0.66, 1.27]
  4 studies · 493 participants
  Low

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  no estimate extracted
  3 studies · 136 participants
  Moderate

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  no estimate extracted
  8 studies · 1203 participants
  Moderate

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

Clomiphene citrate or letrozole with or without gonadotropins (with… may leads to lower ovarian hyperstimulation syndrome per woman compared with gonadotropins (with GnRH agonists or midcycle antagonist) (low certainty).

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  Peto OR 0.21 [0.11, 0.41]
  5 studies · 1067 participants
  Low

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

Clomiphene citrate or letrozole with or without gonadotropins (with… showed no clear difference in clinical pregnancy rate per woman compared with gonadotropins (with GnRH agonists or midcycle antagonist) (moderate certainty).

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  RR 1 [0.86, 1.16]
  12 studies · 1998 participants
  Moderate

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

Clomiphene citrate or letrozole with or without gonadotropins (with… may leads to higher cancellation rate per woman compared with gonadotropins (with GnRH agonists or midcycle antagonist) (low certainty).

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  RR 1.87 [1.43, 2.45]
  9 studies · 1784 participants
  Low

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  no estimate extracted
  6 studies · 1098 participants
  Moderate

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  no estimate extracted
  8 studies · 1481 participants
  Moderate

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

Clomiphene citrate or letrozole with or without gonadotropins (with… showed no clear difference in live birth per woman compared with gonadotropins (with GnRH agonist or midcycle antagonist) (low certainty).

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  RR 1.16 [0.49, 2.79]
  2 studies · 357 participants
  Low

Clomiphene citrate or letrozole with or without gonadotropins (with or without midcycle antagonist) vs gonadotropins (with GnRH agonists or midcycle antagonist)

Clomiphene citrate or letrozole with or without gonadotropins (with… showed no clear difference in clinical pregnancy rate per woman compared with gonadotropins (with GnRH agonist or midcycle antagonist) (low certainty).

• Oral medications including clomiphene citrate or aromatase inhibitors with gonadotropins for controlled ovarian… 2017 · Cochrane Headline outcomes only
  RR 0.85 [0.64, 1.12]
  8 studies · 1462 participants
  Low