Table 4.

Comparison of our study with previous studies assessing the effect of OSCM HSG on the newborn's thyroid.

Study reference	Type of study	Country	Number of newborns with thyroid dysfunction	Volume of OSCM (Lipiodol) used during mother's HSG	Newborn screening strategy	Number of months between OSCM exposure and conception
Satoh et al. (2015) [25]	RSa	Japan	5 out of 212 OSCM HSGs	10 ml, 20 ml, 20 ml, NR, and NR	TSH-based screening	1, 1, 2, 3, and 12
Li et al. (2018) [29]	PSb	China	None out of 36 OSCM HSGs	NRc	TSH-based screening at 72+ hours	NR
Van Welie et al. (2020) [28]	RS	The Netherlands	None out of 76 OSCM HSGs	9 ml (6–11.8)	T4 followed by TSH if necessary	2.3 (1.1–4.3)
Our study	RS	New Zealand	None out of 146 OSCM HSGs	NR	TSH-based screening at 48+ hours	0–6
						Median 2
						IQR (1–3)

^aRS: retrospective study; ^bPS: prospective study; ^cNR: not recorded; OSCM: oil-soluble contrast medium; HSG: hysterosalpingography; TSH: thyroid-stimulating hormone; T4: tetraiodothyronine.