Pregnancy outcomes of foetal reduction from twin to singleton gestation compared to ongoing twin gestations: a systematic review and meta-analysis

Figures & data

Figure 1. Flow diagram for the selection of studies and specific reasons for exclusion from the present meta-analysis.

Table1. Characteristics of the included studies comparing pregnancy outcomes of foetal reduction from twin to singleton gestation compared to ongoing twin gestations.

Study	Country	Study duration	Groups	Sample size (n)	Age_MPR	Indications of twin reduction	Mode of conception	Approach of MPR	Twin type	Gestational age at MPR	Definition of preterm birth	PTB_37 week _MPR	PTB_37 week Control	PTB_34 week _MPR	PTB_34 week _Control	Definition of miscarriage	Adjusted variable for analysis
Vieira et al. (2019)	USA	2008–2016	MPR Control	250 605	37.56 ± 4.67 35.44 ± 6.13		Spontaneous or ART	Transabdominal	DC–DA	11–15 weeks	<37 weeks	43	322	17	102	<24 weeks	NA
Luo et al. (2019)	China	2009–2015	MPR Control	71 710	31 (29,35) 31 (29,35)		IVF	Transvaginal	DC–DA	7–8 weeks	<37 weeks	9	327			<28 weeks	Maternal age, education of the couples, parity, BMI, infertility type, main causes of infertility, type and number of embryos transferred and whether the embryos were frozen–thawed
Shu et al. (2017)	China		MPR Control	102 4638			IVF	Transvaginal	DC–DA	6.5–10.5 weeks	<37 weeks	11	1934			<28 weeks	Maternal age, infertility type, infertility duration and BMI
Van de Mheen et al. (2015)	Netherlands	2000–2010	MPR Control	118 818	35.7 (32.6–38.8) 35.1 (31.6–38)		Spontaneous or ART	Transabdominal	DC–DA	10–23 weeks	<37 weeks			22	94	<24 weeks	NA
Haas et al. (2015)	Israel	2005–2012	MPR Control	63 62	35 (25–46) 35 (29–53)		Spontaneous or ART	NA	DC–DA	11–14 weeks	<37 weeks	6	34	1	7	<24 weeks	Maternal age, parity and mode of conception
Hasson et al. (2011)	Israel	2000–2007	MPR Control	32 5	34.5 ± 5 36.2 ± 4.3		Spontaneous or ART	NA	DC–DA	12–35 weeks	NA	6	9	4	4	NA	Maternal age, parity
Gupta et al. (2015)	USA	2005–2023	MPR Control	63 496	37 ± 4.6 34 ± 6.6		Spontaneous or ART	Transabdominal	DC–DA	11–24 weeks	<37 weeks	6	215	3	60	NA	Maternal age, ethnicity and presence of Müllerian anomalies
Greenberg et al. (2020)	Israel	2005–2018	MPR Control	98 222	34.1 ± 5 33.6 ± 5		Spontaneous or IVF or Hyperstimulation	Transabdominal	DC–DA	11–34 weeks	<37 weeks	38	128	12	41	NA	Parity and conception
Kaul et al. (2021)	India	2015–2018	MPR Control	35 421	31.7 ± 4.07 31.6 ± 3.79		Spontaneous or ART	Transabdominal	DC–DA	11–14 weeks	<37 weeks	7	170	0	66	NA	Age, parity, BMI
Kristensen et al. (2023)	Austria	2008–2018	MPR Control	172 9563	34 (30–39) 30 (26–33)		IUI or IVF or ovulation induction	Transabdominal	DC–DA	Up to 14 weeks	<37 weeks					NA	Gender and GA at delivery
Zemet et al. (2020)	Israel	2005–2016	MPR Control	62 223	34 (31–37) 32 (29–36)		ART	Transabdominal	DC–DA and TCDA	Up to 14 weeks	<37 weeks	8	124	2	44	NA	Maternal age, parity, mode of conception and GA at reduction, reduction of triplets to twins
Gao et al. (2022)	China	2012–2020	MPR Control	49 112	33.5 ± 6.6 36.9 ± 4.0		Spontaneous or IVF or AI	Transabdominal	DC–DA	Up to 24 weeks	<37 weeks	23	79	4	2	NA	NA
Yimin et al. (2022)	China	2002–2016	MPR Control	126 2788	33 (29–35) 30 (28–33)		IVF or ICSI	Transvaginal	DC–DA	NA	<37 weeks	21	1240	7	281	NA	GA at delivery

DC–DA: dichorionic–diamniotic; NA: not available, MPR: multifetal pregnancy reduction; GA: gestational age; BMI: body mass index; IVF: in vitro fertilisation; ART: assisted reproductive technology; BW: birth weight; PTB: preterm birth.

Table 2. Quality assessment of the included studies based on Newcastle-Ottawa Scale (NOS).

S. no.	Newcastle–Ottawa Scale
	Study	Selection				Comparability	Outcome			Total score
		Representativeness of exposed cohort	Selection of non-exposed cohort	Ascertainment of exposure	Demonstration that outcome of interest was not present at start of study	Comparability of cohorts in terms of design or analysis	Assessment of outcome	Follow up was long enough for outcomes to occur	Adequacy of follow up of cohorts
1	Vieira et al. (2019)	1	1	0	1	1	1	1	0	6
2	Luo et al. (2019)	1	1	0	1	1	1	1	1	7
3	Shu et al. (2017)	1	1	1	1	1	1	1	1	8
4	Van de Mheen et al. (2015)	1	1	0	1	1	1	1	0	6
5	Haas et al. (2015)	1	1	0	1	1	1	1	1	7
6	Hasson et al. (2011)	1	1	0	1	1	1	1	1	7
7	Gupta et al. (2015)	1	1	0	1	1	1	1	1	7
8	Greenberg et al. (2020)	1	1	1	1	1	1	1	1	8
9	Kaul et al. (2021)	1	1	1	1	0	0	1	1	6
10	Kristensen et al. (2023)	1	1	1	1	1	1	1	1	8
11	Zemet et al. (2020)	1	1	0	1	1	1	1	1	7
12	Gao et al. (2022)	1	1	1	1	1	1	1	1	8
13	Yimin et al. (2022)	1	1	1	1	1	1	1	1	8

Figure 2. Forest plot for the association of diabetes mellitus between foetal reduction from twin to singleton gestation and control group.

Figure 3. Forest plot for the association of hypertension between foetal reduction from twin to singleton gestation and control group.

Figure 4. Forest plot for the association of caesarean between foetal reduction from twin to singleton gestation and control group.

Figure 5. Forest plot for the association of foetal loss between foetal reduction from twin to singleton gestation and control group.

Figure 6. Funnel plot for the association of (a) diabetes mellitus, (b) hypertension, (c) caesarean delivery and (d) foetal loss between foetal reduction from twin to singleton gestation and control group.

Figure 7. Sensitivity analysis for the association of diabetes mellitus between foetal reduction from twin to singleton gestation and control group.

Vieira, L.A., et al., 2019. Comparing pregnancy outcomes and loss rates in elective twin pregnancy reduction with ongoing twin gestations in a large contemporary cohort. American Journal of Obstetrics and Gynecology, 221 (3), 253.e1–253.e8.

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Kaul, A., et al., 2021. Elective fetal reduction in dichorionic diamniotic twin pregnancies on parental request: a single-centre experience. Fetal Diagnosis and Therapy, 48 (4), 272–278.

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Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.