Table 1.

Comparisons of obstetrical outcomes between spontaneously conceived and IVF pregnancies

Authors	Year	Study format	Singletons	Twins	Comments
Källén et al [11]	2010	National		X	Significant increase in IVF of PTB (<32 weeks); No difference in LBW
Pinborg et al [15]	2013	Review	AOR 1.27, (95 % CI 1.08, 1,49)		Even in same mother an IVF offspring has more PTB than non-IVF Offspring
Sazonova et al [7]	2013	This study is only indirectly relevant to here reviewed subject but is listed because it is the only study, which correctly compared in a large national population outcomes of twin pregnancies in comparison to two consecutive singleton pregnancies. Unfortunately, as previously in detail reviewed by us, the authors misrepresented their data in discussing their conclusions [9]. A correct analysis of their data demonstrated no clinically significant outcome differences in either maternal or neonatal outcomes, with AORs listed in the reference. The study, however, did not comment on differences between spontaneously- and IVF-conceived pregnancies.
Anbazahagan et al [12]	2014	MCPT	no significant difference	X	No difference between IVF and spont. twins but small size and prospective study
Henningsen et al [16]	2014	Scandinavian population study	AOR 1.54 (95 % CI 1.28, 1.85)	X	IVF singletons had increased neonatal death risk. IVF twins had lower risk, which was lost when restricted to opposite-sex twins
Dar et al [13]	2014	Review and meta-analysis; Study does not comment on differences In outcomes between spontaneously and IVF-conceived singletons and twins but demonstrates significantly increased PTB risk for blastocyststage embryo transfer in comparison to cleavage-stage embryo transfer, a finding with relevance to here discussed topic since blastocyst-stage embryo transfer is a prerequisite for eSET.
Declercq et al [17]	2015	Cohort	AOR for PTB 1.23AOR for LBW 1.26		Both AORs are in comparison to a subfertile patient group: Risks of singletons among IVF patients and in a sub-fertile patient group were, both, higher than in normally fertile population.
				AOR for PD 0.55 in comparison to fertile controls
				AOR for PF 0.15 in comparison to subfertile controls
Henningsen et al [14]	2015	Cross-border Scandinavian cohort study demonstrating significant declines over last 20 years in stillbirth and infant deaths for IVF singletons and twin deliveries, with “fewer” IVF twins being stiiborn or died during year 1 of life compared to spontaneously conceived twins (presumably due to fewer monozygotic twins among IVF twins). In addition IVF singletons demonstrated a significant decline in being born preterm and very preterm.

AOR adjusted odds ratio; PTB preterm birth; X – in comparison to; MCPT multicenter prospective trial, LBW low birth weight; PD, perinatal death