Table 1.
Demographic and clinical characteristics of all births to nulliparous women in British Columbia (Canada), 2004–2014, N (%).
| All 203,414 |
<20 years 11,524 |
20–<25 years 36,510 |
25–<30 years 62,214 |
30–<35 years 60,616 |
35–<40 years 26,708 |
40–<45 years 5,426 |
≥45 years 416 |
|
|---|---|---|---|---|---|---|---|---|
| Pre-pregnancy type 1 or type 2 diabetes | 1,010 (1) | 26 (0) | 125 (0) | 283 (1) | 298 (1) | 214 (1) | 56 (1) | 8 (2) |
| Pre-pregnancy hypertension | 1,078 (1) | <5 (0) | 63 (0) | 2225 (0) | 371 (2) | 288 (1) | 114 (2) | 12 (3) |
| Current smoker | 18,389 (9) | 3,516 (31) | 6,669 (18) | 4,401 (7) | 2,563 (4) | 1,017 (4) | 216 (4) | 7 (2) |
| Obesea (BMI≥30) | 15,660 (11) | 491 (7) | 2,981 (12) | 5,054 (11) | 4,548 (10) | 2,137 (11) | 421 (11) | 28 (10) |
| Inadequate antenatal careb | 12,413 (7) | 1,426 (13) | 2,742 (8) | 3,377 (6) | 3,036 (5) | 1,503 (6) | 304 (6) | 25 (7) |
| Low income (≤2nd income decile)c | 43,820 (22) | 3,707 (32) | 9,421 (26) | 13,144 (21) | 11,586 (19) | 4,913 (18) | 979 (18) | 70 (17) |
| Rural residenced | 21,427 (11) | 2,604 (23) | 6,094 (17) | 6,129 (10) | 4,445 (7) | 7,798 (7) | 334 (6) | 23 (6) |
| Previous spontaneous or induced abortion | 59,516 (29) | 2,098 (18) | 9,546 (26) | 16,172 (26) | 18,285 (30) | 10,431 (39) | 2,751 (51) | 233 (56) |
| Diagnosed infertility | 25,961 (13) | 55 (1) | 1,137 (3) | 5,239 (8) | 9,177 (15) | 7,498 (28) | 2,556 (47) | 299 (72) |
| Non-IVF infertility treatment/evaluation | 1,283 (0) | 0 (0) | 17 (0) | 180 (0) | 465 (0) | 416 (1) | 181 (1) | 24 (2) |
| In vitro fertilizatione | 5,286 (4) | 29 (0) | 91 (0) | 613 (2) | 1,630 (4) | 1,922 (12) | 816 (23) | 185 (67) |
| Low risk profilef | 38,851 (19) | 1,450 (13) | 16.6 (17) | 13,760 (22) | 13,035 (22) | 4,039 (15) | 506 (9) | 10 (2) |
BMI indicates body mass index, IVF in vitro fertilization.
Pre-pregnancy weight or maternal height was missing for 53,828 (26.5%) observations.
Number of antenatal visits is missingin 16,191 (8.0%).
Missing census tract decile for the year of birth (n=31,249; 15.4%) was imputed using census tract decile from the closest year with available data. Those with no census tract data for any year (n=5,590; 2.8%) were imputed using multiple imputation.
Missing community size (used to define rural residence) for the year of birth (n=28,300, 13.9%) was imputed using community size data from the closest year with available data. Those with no community size data for any year (n=2,613; 1.3%) were imputed using multiple imputation. Infertility treatment or evaluation defined as outpatient prescription of clomid or letrazole, or billing codes for artificial insemination or post coital test.
In vitro fertilization was not collected until April 1, 2008; IVF data in this table are restricted to April 1, 2008 – March 31, 2014.
Low risk profile defined as the absence of all age-related risk factors: no pre-pregnancy diabetes or hypertension, not a current smoker, not obese, received adequate antenatal care, urban residence, no previous known spontaneous or induced abortion,