My clinical and research interests are in reproductive medicine. My main research areas are management of infertility, emergency contraception, medical abortion and clinical applications of mifepristone and misoprostol.

1. Chan CC, Ng EH, Tang OS, Yeung WS, Lau EY, Ho PC. A prospective, randomized, double-blind study to compare two doses of recombinant human chorionic gonadotropin in inducing final oocyte maturity and the hormonal profile during the luteal phase. J Clin Endocrinol Metab. 2005 Jul;90(7):3933-8.
2. Ng EH, Chan CC, Yeung WS, Ho PC. Comparison of ovarian stromal blood flow between fertile women with normal ovaries and infertile women with polycystic ovary syndrome. Hum Reprod. 2005 Jul;20(7):1881-6.
3. Ngai SW, Fan S, Li S, Cheng L, Ding J, Jing X, Ng EH, Ho PC. A randomized trial to compare 24 h versus 12 h double dose regimen of levonorgestrel for emergency contraception. Hum Reprod. 2005 Jan;20(1):307-11.
4. Ng EH, Naveed F, Lau EY, Yeung WS, Chan CC, Tang OS, Ho PC. A randomized double-blind controlled study of the efficacy of laser-assisted hatching on implantation and pregnancy rates of frozen-thawed embryo transfer at the cleavage stage. Hum Reprod. 2005 Apr;20(4):979-85.
5. Tang OS, Lau WN, Chan CC, Ho PC. A prospective randomised comparison of sublingual and vaginal misoprostol in second trimester termination of pregnancy. BJOG. 2004 Sep;111(9):1001-5.
6. Tang OS, Mok KH, Ho PC. A randomized study comparing the use of sublingual to vaginal misoprostol for pre-operative cervical priming prior to surgical termination of pregnancy in the first trimester. Hum Reprod. 2004 May;19(5):1101-4.
7. Tang OS, Chan CC, Ng EH, Lee SW, Ho PC. A prospective, randomized, placebo-controlled trial on the use of mifepristone with sublingual or vaginal misoprostol for medical abortions of less than 9 weeks gestation. Hum Reprod. 2003 Nov;18(11):2315-8.
8. Tang OS, Lee SW, Ho PC. A prospective randomized study on the measured blood loss in medical termination of early pregnancy by three different misoprostol regimens after pretreatment with mifepristone. Hum Reprod. 2002 Nov;17(11):2865-8.
9. Tang OS, Ho PC. Medical abortion in the second trimester. Best Pract Res Clin Obstet Gynaecol. 2002 Apr;16(2):237-46. Review.
10. Ho PC, Yu Ng EH, Tang OS. Mifepristone: contraceptive and non-contraceptive uses. Curr Opin Obstet Gynecol. 2002 Jun;14(3):325-30. Review.