thats why I said 'actually works' cause afaik that friggin does not work
The Extreme Pregnancy Hormones (Tier 3) works fine, though it depends on what else you add into the mix. Once I unlock that one I create a simple new serum consisting of:
Primitive Serum Production (Tier 0)
Self Replicating Serum (Tier 3)
Extreme Pregnancy Hormones (Tier 3)
Name it whatever you want, put it into production and start handing out the serum to your pregant ladies. By including the Self Replicating Serum (Tier 3) it will last way longer which means a much greater effect to the reduction time of the pregnancy, though the overall effect will depend on how far the subject's pregnancy has already progressed. I give it to my subjects within a day or two of them telling me that they are pregnant and within days they start showing the early signs of pregnancy.
Increasing the Mastery of unlocked serums will help, I usually keep my R&D team researching specific serums until the serum gets to around 100% Mastery so as to reduce the chance of side effects to 0%.