TABLE 1.
Characteristics of fresh elective single ETs (eSET) and fresh elective double ETs (DET) among patients younger than 35 years of age with no prior ART cycles who cryopreserved at least one embryo in 2012.
| eSET (n = 4,129) | DET (n = 10,001) | ||||
|---|---|---|---|---|---|
| Characteristic | N | % | N | % | P value |
| Age (y) | .63 | ||||
| ≤30 | 1,872 | 45.3 | 4,602 | 46.0 | |
| 31–32 | 1,168 | 28.3 | 2,743 | 27.4 | |
| 33–34 | 1,089 | 26.4 | 2,656 | 26.6 | |
| Gravidity | .39 | ||||
| 0 | 2,657 | 64.5 | 6,363 | 63.8 | |
| 1 | 839 | 20.4 | 1,990 | 20.0 | |
| ≥2 | 623 | 15.1 | 1,618 | 16.2 | |
| Parity | .07 | ||||
| 0 | 3,394 | 82.5 | 8,406 | 84.4 | |
| 1 | 546 | 13.3 | 1,123 | 11.3 | |
| ≥2 | 174 | 4.2 | 430 | 4.3 | |
| Racea | <.001 | ||||
| Non-Hispanic white | 2,110 | 73.1 | 5,007 | 73.0 | |
| Non-Hispanic black | 160 | 5.5 | 452 | 6.6 | |
| Asian/Pacific Islander | 429 | 14.9 | 730 | 10.6 | |
| Hispanic | 182 | 6.3 | 661 | 9.6 | |
| Other | 5 | 0.2 | 14 | 0.2 | |
| Body mass index (BMI)a | <.001 | ||||
| <18.5 | 133 | 3.8 | 252 | 3.1 | |
| 18.5–24.9 | 2,030 | 58.6 | 4,450 | 55.0 | |
| 25–29.9 | 800 | 23.1 | 1,951 | 24.1 | |
| ≥30 | 500 | 14.4 | 1,442 | 17.8 | |
| ART diagnoses (not mutually exclusive) | |||||
| Female factor infertility | |||||
| Diminished ovarian reserve | 178 | 4.3 | 641 | 6.4 | <.001 |
| Endometriosis | 365 | 8.8 | 1,217 | 12.2 | <.001 |
| Ovulation disorders | 986 | 23.9 | 2,264 | 22.6 | .16 |
| Tubal factor | 574 | 13.9 | 1,596 | 16.0 | .02 |
| Uterine factor | 178 | 4.3 | 362 | 3.6 | .11 |
| Male factor infertility | 1,586 | 38.4 | 4,183 | 41.8 | .006 |
| Other reason for infertility | 487 | 11.8 | 898 | 9.0 | <.001 |
| Unexplained infertility | 734 | 17.8 | 1,449 | 14.5 | <.001 |
| No. of oocytes retrieved | <.001 | ||||
| 2–4 | 43 | 1.0 | 81 | 0.8 | |
| 5–9 | 486 | 11.8 | 1,472 | 14.7 | |
| 10–14 | 1,007 | 24.4 | 2,882 | 28.8 | |
| 15–19 | 1,102 | 26.7 | 2,629 | 26.3 | |
| ≥20 | 1,491 | 36.1 | 2,937 | 29.4 | |
| Assisted hatching | 539 | 13.1 | 2,391 | 23.9 | <.001 |
| Intracytoplasmic sperm injection | 2,843 | 68.9 | 7,797 | 78.0 | <.001 |
| Preimplantation genetic diagnosis | 245 | 5.9 | 326 | 3.3 | <.001 |
| Embryo stageb | <.001 | ||||
| Cleavage (day 2–3) | 371 | 9.0 | 2,927 | 29.3 | |
| Blastocyst (day 5–6) | 3,721 | 90.1 | 6,862 | 68.6 | |
| No. of embryos cryopreserved | <.001 | ||||
| 1–2 | 1,141 | 27.6 | 4,045 | 40.5 | |
| 3–5 | 1,654 | 40.1 | 3,640 | 36.4 | |
| ≥6 | 1,334 | 32.3 | 2,316 | 23.2 | |
Note: ART = assisted reproductive technology.
a
Race data were missing for 30% of the eSET group and 31% of the DET group. BMI data were missing for 16% of the eSET group and 19% of the DET group. Percentages and P values were calculated for the data available.
b
A small percentage of transfers occurred on days 1 and 4. Data not shown.