Conception probabilities at different days of menstrual cycle in Chinese women.
OBJECTIVE
To investigate the conception probability among Chinese women.


METHODS
Prospective observational study.


METHODS
Clinics in hospitals and family planning institutes in 10 provinces and cities.


METHODS
A total of 851 healthy married women aged 18-35 years with normal menstrual cycles who wish to have babies and with no contraception.


METHODS
Urinary LH was measured around days of expected ovulation for 7 days. The Barrett and Marshall model was used for calculation of conception probabilities on each cycle day from day -5 to day +1 in women with multiple episodes of intercourse.


METHODS
Pregnancies in 1, 3, and >or=6 months.


RESULTS
A total of 851 women with 2,055 cycles were analyzed. In 489 cycles there was only one episode of intercourse. A total of 601 pregnancies occurred. The conception probabilities from days in relation to ovulation -5 to +1 for a single episode of intercourse were 0.216, 0.102, 0.236, 0.233, 0.388, 0.293, and 0.386, respectively, and for multiple episodes they were 0.254, 0.271, 0.293, 0.365, 0.315, and 0.284, respectively, with the peak value at day -1. Recalculation of the efficacy of emergency contraception with low-dose mifepristone with the present conception probabilities showed higher efficacy.


CONCLUSIONS
Conception probabilities among Chinese women are different from those in the literature. Further comparative studies are needed to confirm an ethnic difference.
Bilian
Xiao
X
National Research Institute for Family Planning, Beijing, People's Republic of China. Electronic address: xiaobilian@yahoo.com.
Heng
Zhao
Z
Hai Hui Information Science and Technology Center, Beijing, People's Republic of China.
Shang-Chun
Wu
W
National Research Institute for Family Planning, Beijing, People's Republic of China.
Xiao-Ping
Jing
J
Chao Yang Hospital, Beijing, People's Republic of China.
Chang-Hai
He
H
Shanghai Institute of Planned Parenthood Research, Shanghai, People's Republic of China.
Wen-Qi
Shao
S
Qingdao Family Planning Institute, Qingdao, People's Republic of China.
Zhen-Wu
Lei
L
Sichuan Reproductive Health Institute, Sichuan, Chengdu, People's Republic of China.
D000293:Adolescent; D000328:Adult; D044466:Asian People / Q000706:statistics & numerical data; D003075:Coitus / Q000502:physiology; D044363:Contraception, Postcoital / Q000706:statistics & numerical data; D005260:Female; D005306:Fertilization / Q000502:physiology; D006801:Humans; D007986:Luteinizing Hormone / Q000652:urine; D008597:Menstrual Cycle / Q000502:physiology*; D010060:Ovulation / Q000502:physiology / Q000652:urine; D011247:Pregnancy; D011256:Pregnancy Outcome; D018873:Pregnancy Rate / Q000208:ethnology*; D011336:Probability; D013997:Time Factors; D055815:Young Adult
D007986:Luteinizing Hormone