Table 2.

Difference in birthweight between infants born following fresh embryo transfer and those born following frozen/thawed embryo transfer for all variables included in the model, stratified by infant sex. Term, live-born, autologous embryo transfer infants born in the U.S. between 2007 and 2014 (n=180,184), National ART Surveillance System (NASS).

	Birthweight for All Infants (grams)			Birthweight for Female Infants (grams)			Birthweight for Male Infants (grams)
	N=180,184			N=89,007			N=91,177
Obstetric and Infant variables	Est.	Std. Error	P	Est.	Std. Error	P	Est.	Std. Error	P
Fresh Embryo Transfer	−142.34	2.68	<0.001	−134.09	3.73	<0.001	−150.28	3.85	<0.001
Female Sex	−142.51	2.02	<0.001	–	–	–	–	–	–
Gestational Age in Days	154.71	0.99	<0.001	152.35	1.39	<0.001	157.03	1.42	<0.001
Maternal Demographics
Maternal Age in Years	1.04	0.27	<0.001	1.23	0.37	0.001	0.83	0.38	0.029
Year of Treatment	−4.40	0.45	<0.001	−4.29	0.63	<0.001	−4.50	0.65	<0.001
Infertility Diagnosis (nonexclusive)
Male Factor	14.58	2.64	<0.001	16.57	3.68	<0.001	12.53	3.80	0.001
Diminished Ovarian Reserve	−13.47	3.31	<0.001	−14.57	4.59	0.002	−12.41	4.78	0.009
Uterine Factor	−9.50	5.28	0.072	−8.05	7.38	0.276	−11.27	7.56	0.136
Endometriosis	12.06	3.43	<0.001	10.43	4.73	0.028	13.43	4.97	0.007
Ovulatory Disorder or Polycystic Ovaries	18.73	3.09	<0.001	24.22	4.32	<0.001	13.19	4.43	0.003
Tubal Factor	1.51	3.3	0.648	10.36	4.60	0.024	−7.42	4.75	0.118
Other Cause	2.59	3.42	0.447	13.27	4.77	0.005	−7.81	4.89	0.110
Unexplained	0.35	3.85	0.929	7.42	5.38	0.168	−6.70	5.51	0.224
Maternal Pregnancy History
Number of Previous ART Cycles*
No previous cycles	Ref.			Ref.			Ref.
1–2 cycles	14.05	2.58	<0.001	12.76	3.60	<0.001	15.13	3.70	<0.001
3 or more cycles	11.63	3.56	0.001	8.66	4.91	0.078	14.57	5.14	0.005
One or More Previous Miscarriage(s)*	9.90	2.32	<0.001	1.98	3.23	0.539	17.37	3.33	<0.001
Parity*
One to two previous births	Ref.			Ref.			Ref.
No previous births	−114.57	2.36	<0.001	−107.91	3.28	<0.001	−121.47	3.38	<0.001
3 or more previous births	3.02	7.38	0.683	−3.82	10.31	0.711	9.48	10.52	0.367
Maternal Ethnicity**
Non-Hispanic White	Ref.			Ref.			Ref.
Non-Hispanic Black	−65.72	7.79	<0.001	−68.44	10.56	<0.001	−62.73	11.71	<0.001
Asian or Pacific Islander	−53.31	4.71	<0.001	−52.04	7.13	<0.001	−54.01	7.30	<0.001
Hispanic	−29.15	5.46	<0.001	−27.37	8.10	0.001	−30.72	7.74	<0.001
Other	−56.97	23.31	0.015	−59.13	34.85	0.090	−51.37	32.70	0.116
Paternal Ethnicity**
Non-Hispanic White	Ref.			Ref.			Ref.
Non-Hispanic Black	−12.82	7.59	0.092	−4.92	10.76	0.647	−20.80	11.91	0.084
Asian or Pacific Islander	−67.04	5.01	<0.001	−54.73	7.79	<0.001	−78.84	7.47	<0.001
Hispanic	−27.32	5.63	<0.001	−22.19	8.02	0.006	−32.51	8.18	<0.001
Other	−37.82	16.22	0.023	−60.40	21.24	0.005	−15.57	22.14	0.485

Model is controlled for all variables in the table. Participants with missing data for variables indicated with an asterisk (*) were excluded. Missing data for maternal and paternal race were imputed(**). No other data was missing. Est.= Estimate; Std. Error=Standard Error; Ref.=Reference