A study published in the September 2022 issue of Obstetrics & Gynecology Research shows an association between positive PdG cycles and increased pregnancy rates, along with reduced chances of first-trimester pregnancy loss.

Beckley A, Koudele A, Park J, et al. The predictive value of urinary progesterone metabolite PdG testing in pregnancy outcomes. Obstetrics and Gynecology Research. 2022;5(2022):194–198.

The study was sponsored by Proov, the manufacturer of the first and only FDA-approved PdG-test and the first full-cycle tracking kit.

Study results

Researchers were able to correlate positive cycles of the major progesterone (P4) metabolite pregnanediol-3-glucuronide (PdG), which is used to confirm ovulation, with a 75% increase in pregnancy rates as well as a decrease in first-trimester pregnancy losses related to low progesterone. While testing for PdG may provide useful feedback about the quality of the cycle, it should be noted that the test itself doesn’t affect the outcome of a pregnancy.

The goal of the study, which had 185 participants, was to "give a complete picture of progesterone production across the luteal phase required for pregnancy," according to the authors.

The luteal phase occurs after ovulation, continues through the next menstruation or through pregnancy, and is responsible for progesterone secretion. The luteal phase is triggered by luteinizing hormone (LH.) After the dominant follicle ruptures, releasing an oocyte, the dominant follicle becomes the corpus luteum, which secretes progesterone in preparation for pregnancy.

If fertilization occurs, the corpus luteum continues to secrete progesterone until the first 6–8 weeks of pregnancy; then the placenta takes over. If fertilization does not occur or if enough progesterone is not secreted, the corpus luteum breaks down, resulting in menstruation. Therefore, progesterone is crucial for pregnancy to occur, and PdG testing can help determine if a woman has low progesterone during pre-conception.

van der Linden M, Buckingham K, Farquhar C, et al. Luteal phase support for assisted reproduction. Cochrane. July 7, 2015.

This study suggests the use of LH and PdG testing as preconception screening tools to help identify subfertility in women and the probability of first-trimester loss of pregnancies due to low progesterone. If a woman who is trying to conceive has a negative PdG cycle, she can potentially use medications that help to induce LH and progesterone secretion at the preconception stage, which can potentially decrease the need for IVF treatments.

At-home urinary PdG testing over four days offers a noninvasive method of monitoring mid-luteal activity and can be used as a marker of luteal health.

"It is a more patient-friendly way to assess for progesterone deficiency and provides a more complete picture of luteal function when compared to a brief snapshot of one serum progesterone level," the study authors continued.

Ovulation test scrutiny

Ovulation tests are the focus of a lawsuit against major manufacturers (including Clearblue, First Response, Up&Up, and CVS Health) contending that their tests are unreliable and misleading to consumers, impacting their conception chances by providing incomplete information.