Table 2. Characteristics of included studies.

MPs: microplastics.

Reference	Year	Country	Participants (n)	Study design	Mode of delivery	Clinical samples	Detection method	Microplastics	Size of MPs	MPs detected	Risk of bias
Xue et al. [25]	2024	China	40	Prospective cohort	Vaginal	Amniotic fluid	Laser direct infrared spectroscopy	Chlorinated Polyethylene Polyethylene	20-100 μm	32 out of 40 amniotic fluid samples	Low
Hasanah et al. [20]	2024	Malaysia	30	Prospective cohort	NR	Stool	Fourier-transform infrared microspectroscopy	Chlorinated Polyethylene Polypropylene Terephthalate Polyamide/Nylon	0.2-4.9 mm	30 out of 30 stool samples	Low
Zurub et al. [5]	2024	Canada	10	Cross-sectional	Vaginal/ Caesarean	Placenta	Light microscopy and Raman microspectroscopy	Polyethylene Polystyrene Polyvinyl chloride	2-60 µm	10 out of 10 placentas	Low
Liu et al. [10]	2023	China	18	Prospective cohort	Vaginal	Placenta Meconium	Laser direct infrared spectroscopy	Polyethylene Polyurethane Polyamide	20-50 µm	18 out of 18 placentas and 18 out of 18 meconium specimens	Moderate
Halfar et al. [8]	2023	Czech Republic	10	Prospective cohort	Preterm birth	Placenta Amniotic fluid	Fourier-transform infrared microspectroscopy	Chlorinated Polyethylene Calcium Zinc PVC stabilizer	20-50 µm	9 out of 10 placentas and amniotic fluid specimens	Moderate
Weingrill et al. [26]	2023	USA	30	Retrospective cohort	NR	Placenta	Light microscopy and Raman microspectroscopy	Polyethylene Polyurethane Polyamide	1-44 µm	6 out of 10 placentas in 2006, 9 out of 10 placentas in 2013, and 10 out of 10 placentas in 2021	Moderate
Zhu et al. [27]	2023	China	17	Cross-sectional	Vaginal	Placenta	Laser direct infrared spectroscopy	Polyethylene Polystyrene Polyurethane	<100 µm	17 out of 17 placentas	Low
Ragusa et al. [13]	2022	Italy	10	Cross-sectional	Vaginal/ Caesarean	Placenta	Variable pressure scanning electron microscopy and transmission electron microscopy	Polyethylene	2.1-18.5 µm	10 out of 10 placentas	Low
Liu et al. [11]	2022	China	18	Cross-sectional	Vaginal	Placenta Meconium	Laser direct infrared spectroscopy	Polyamide Polyurethane	20-50 µm	18 out of 18 placentas and 12 out of 12 meconium specimens	Moderate
Amereh et al. [28]	2022	Iran	43	Case–control	Vaginal	Placenta	Light microscopy and Raman microspectroscopy	Polyethylene Polystyrene	<10 µm	In the normal group, 4 out of 30 placentas. In the IUGR group, 13 out of 13 placentas	Moderate
Ragusa et al. [12]	2021	Italy	6	Cross-sectional	Vaginal	Placenta	Light microscopy and Raman microspectroscopy	Polyethylene	5-10 µm	4 out of 6 placentas	Low
Braun et al. [17]	2021	Germany	2	Cross-sectional	Cesarean	Placenta Meconium	Fourier-transform infrared microspectroscopy	Polyethylene Polypropylene Polystyrene Polyurethane	<50 µm	2 out of 2 placentas and 2 out of 2 meconium specimens	Moderate