Received May 19, 2021
Accepted November 29, 2021

ABSTRACT One of the most widely accepted axioms of reproductive biology is that pregnancy requires the sole support of progesterone, without which pregnancy cannot be established or maintained. We report a rare case of ongoing third trimester pregnancy where early gestational period was maintained despite extremely low progesterone levels of <1ng/ml and was discovered during controlled ovarian hyperstimulation (COS) for in vitro fertilization (IVF), in a 41-year-old woman. She was started on ovarian stimulation (OS) with gonadotrophins after a withdrawal bleed during lactational amenorrhea. Base line investigations on day 2 of menstruation confirmed low serum estradiol and progesterone levels (<1ng/ml). After 5 days of stimulation on follow up scan a sac like structure was seen in the uterine cavity. Beta hCG levels were done which confirmed the presence of early pregnancy despite progesterone levels below 1ng/ml. COS was stopped, and progesterone support was started. Follow up scan confirmed live intrauterine pregnancy and the fetus is currently growing uneventfully at 31 weeks of gestation.