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. Author manuscript; available in PMC: 2017 Apr 1.
Published in final edited form as: Fertil Steril. 2016 Jan 7;105(4):1014–1022.e1. doi: 10.1016/j.fertnstert.2015.12.043

Table 1.

Comparisons of study population characteristics by mode of conception, Upstate KIDS study (2008-2010)

No Fertility Treatment N=3,230 Fertility Treatment N=1,361 P
n % n %
Maternal Characteristics
Age (years)
≤ 28 1464 45.3 193 14.1 <0.001
> 28 and ≤ 33 1039 32.2 468 34.4
> 33 727 22.5 700 51.4
Missing 0 0
Race
Non-Hispanic white 2523 78.1 1189 87.4 <0.001
Other 707 21.9 172 12.6
Missing 0 0
BMI, post pregnancy (kg/m2)
≤ 24.9 1212 39.9 561 42.7 0.21
> 24.9 and ≤ 29.9 886 29.2 372 28.3
> 29.9 938 30.9 380 28.9
Missing 194 48
Morbiditiesa
Yes 503 16.7 468 36.0 <0.001
Missing 215 62
Number of prior births
0 933 29.1 529 39.1 <0.001
1 992 30.9 419 30.9
2+ 1283 40.0 404 29.9
Missing 22 9
Education completed
≤ High School 725 23.1 78 5.9 <0.001
> High School and ≤ College 1704 54.4 653 49.0
More than college 705 22.5 603 45.2
Missing 96 27
Marital status
Married 2677 85.7 1260 95.5 <0.001
Not Married 446 14.3 60 4.6
Missing 107 41
Private Insurance Status
Has 2157 66.8 1291 94.9 <0.001
Does not have 1071 33.2 70 5.1
Missing 2 0
Doctor visit for difficulty becoming pregnant in past
Yes 267 8.4 462 34.4 <0.001
Missing 62 19
Cesarean birth, index pregnancy
Yes, no trial of labor 1030 32.3 594 43.7 <0.001
Yes, with a trial of labor 339 10.6 196 14.4
Vaginal delivery 1825 57.1 568 41.8
Unknown route of delivery 36 3
Paternal Characteristics
Age (years)b
≤ 30 1277 39.5 231 17.0 <0.001
> 30 and ≤ 35 913 28.3 400 29.4
> 35 780 24.2 681 50.0
Unknown 260 8.1 49 3.6
Missing 0 0
Race
Non-Hispanic white 2436 75.4 1193 87.7 <0.001
Other 793 24.6 168 12.3
Missing 1 0
BMIb
≤ 24.9 847 26.7 257 19.2 <0.001
> 24.9 and ≤ 29.9 1193 37.7 585 43.6
> 29.9 856 27.0 393 29.3
Unknown 272 8.6 107 8.0
Missing 62 19
Morbiditiesa
Yes 398 12.6 244 18.2 <0.001
Missing 62 19
Education completedb
≤ High School 1093 34.5 159 11.9 <0.001
> High School and ≤ College 1582 49.9 778 58.0
More than college 424 13.4 371 27.7
Unknown 69 2.2 34 2.5
Missing 62 19
Infant Characteristics
Preterm (< 37 weeks)
Yes 479 14.8 323 23.7 <0.001
Missing 0 0
Low birth weight (< 2,500 grams)
Yes 407 12.6 268 19.7 <0.001
Missing 0 0
Sex
Male 1695 52.5 684 50.3 0.17
Female 1535 47.5 677 49.7
Missing 0 0
Plurality
Singleton 2647 82.0 957 70.3 <0.001
Twin 583 18.1 404 29.7
Missing 0 0
Daycare initiation at 8 months
Not started 1222 54.5 464 43.1 <0.001
Started <4 months of age 723 32.3 437 40.6
Started >4 months of age 297 13.3 176 16.3
Missing 988 284
Another pregnancy within year since enrollment
Yes 162 8.2 87 8.7 0.610
Missing 1249 364
Cause of infertilityc
Female factor, one type 215 37.7
Male factor 108 18.9
Multiple female factors 64 11.2
Multiple factors, male and female 79 13.8
Other 25 4.4
Unexplained Unknown 80 14.0

N, n=number; P=p-value; kg=kilogram; m=meter

a

Any of the following: diabetes, hypertension, cardiovascular disease, celiac disease, irritable bowel syndrome, Crohn's disease, and/or eating disorders (and/or PCOS, hepatitis, or HIV among mothers only)

b

An indicator variable for item non-response was included in regression analyses using these variables

c

Among the 571 women who conceived with fertility treatment and linked to the Society for Assisted Reproductive Technology - Clinical Outcome Reporting System within New York State. “Female factor, one type” includes diminished ovarian reserve, endometriosis, polycystic ovarian syndrome, tubal factor, and uterine factor.