Fertility Drugs Associated with Thyroid Cancer Risk: A Systematic Review and Meta-Analysis

Table 1

Characteristics of all included studies.

Study	Location	Study size	Study design	Enrollment period	Fertility treatment	Matched/adjusted factors	Follow-up (years)
Ron et al. [10]	Israel	2,575	Retrospective cohort study	1964–1974	Unknown	Unknown	12.3
Althuis et al. [11]	USA	8,422	Retrospective cohort study	1965–1988	Clomiphene, gonadotropins	Study site, age at follow-up, calendar year of follow-up, gravidity at entry, parity at follow-up	18.8
Hannibal et al. [12]	Denmark	54,362	Case-cohort study	1963–1998	Clomiphene, gonadotropins, progesteronr, hCG, GnRH	Age at first live birth, parity status	8.8
Calderon-Margalit et al. [13]	Israel	15,030	Retrospective cohort study	1974–1976	Clomiphene, gonadotropins, other unknown fertility drugs	Age at first birth, geographic origin, social class, education, parity, time to conception, mean body mass index	29
Yli-Kuha et al. [14]	Finland	18,350	cohort study	1996–1998	IVF	Age, marital status, socioeconomic position	7.8
Reigstad et al. [17]	Norway	806,248	Retrospective cohort study	1984–2010	IVF, ICSI, others	Age at start follow-up, parity at entry, method of ART, duration of follow-up	7.3
Brinton et al. [18]	USA	9,892	Retrospective cohort study	1965–1988	Clomiphene, gonadotropins, combination	Race, reproductive status at first clinic visit, reproductive status at follow-up, number of births at follow-up, age at first birth, age at menarche, BMI at first clinic visit, ever smoke, cause of infertility	30
Reigstad et al. [19]	Norway	1,353,724	Retrospective cohort study	1960–1996	Clomiphene citrate, GnRH, gonadotropins, hCG	Birth year, parity, CC exposure, region of present residence, number of children at entry, age at start of follow-up, age at first cancer, types of treatment, number of cycles of ART, dose of clomiphene citrate	18

hCG: human chorionic gonadotropin, GnRH: gonadotropin-releasing hormone, IVF: in vitro fertilization, and ICSI: intracytoplasmic sperm injection.