Emeritus Professor Sittampalam Shanmugaratnam (4 July 1928 – 6 August 2001), also known as Shan Ratnam, was a Singaporean obstetrician and gynaecologist. He was professor and head of the department of Obstetrics and Gynaecology of the National University Hospital of Singapore and specialized in human reproduction research. He was a medical pioneer and leader in the field of Obstetrics and Gynaecology, both in Singapore and internationally. At the peak of his career, he was the Secretary-General of the Asia and Oceania Federation of Obstetrics and Gynaecology (AOFOG) and the President of the International Federation of Obstetrics and Gynaecology.