Spontaneous early pregnancy with very low levels of progesterone during controlled ovarian stimulation-A case report

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 in a 41-year-old woman, where early gestational period was maintained despite extremely low progesterone levels of <1 ng/ml, and was discovered during controlled ovarian hyperstimulation (COS) for in vitro fertilization (IVF). She was started on ovarian stimulation (OS) with gonadotrophins after a withdrawal bleed during lactational amenorrhea. Baseline investigations on day 2 of the menstruation confirmed low serum estradiol and progesterone levels (<1 ng/ml). After 5 days of stimulation, on ultrasound scan, a sac-like structure was seen in the uterine cavity. Beta hCG levels were measured and confirmed the presence of early pregnancy despite progesterone levels below 1 ng/ml. COS was stopped, and progesterone support was started. Subsequent scan confirmed live intrauterine pregnancy and the fetus is currently growing uneventfully at 31 weeks of gestation (at the time of writing this report).