Table 1 Sample characteristics split by sample.

From: A multi-site study of the relationship between photoperiod and ovulation rate using Natural Cycles data

  

Sweden

(n = 56,936)

United States

(n = 326,137)

Age group

 < 25

6739 (11.8%)

50,312 (15.4%)

Between 25 and 30

21,453 (37.7%)

115,111 (35.3%)

Between 30 and 35

19,869 (34.9%)

98,833 (30.3%)

Between 35 and 40

6,421 (11.3%)

44,382 (13.6%)

 > 40

2,454 (4.3%)

17,499 (5.4%)

Parity

No

32,489 (72.7%)

182,487 (76.3%)

Yes, once

6717 (15.0%)

28,836 (12.1%)

Yes, twice

3234 (7.2%)

15,484 (6.5%)

Yes, 3 times or more

2239 (5.0%)

12,454 (5.2%)

Education level

Elementary School

452 (1.0%)

475 (0.2%)

High School

8795 (20.4%)

16,409 (7.5%)

Doctoral Degree

678 (1.6%)

19,612 (8.9%)

Trade/Technical/Vocational Training

4866 (11.3%)

16,197 (7.4%)

University Degree

28,268 (65.6%)

167,555 (76.1%)

Relationship status

Single

4791 (12.9%)

17,811 (8.4%)

It’s complicated

1326 (3.6%)

6460 (3.1%)

In a relationship

23,792 (64.1%)

73,720 (34.9%)

Engaged or married

7202 (19.4%)

113,334 (53.6%)