When I first started to read up on getting pregnant online, I was bombarded with abbrevations I didn't understand at all. Some were logic, others far from it :) So, I actually looked up and wrote down all those I could find and made a list. I hope you find it helpful! At least I would've, had I found something similar before! :D Oh, and if you find a mistake somewhere or have something to add, please let me know! I'll be very happy to update the list!
TTC: Trying To Conceive (well duh.)
CM: Cervical Mucus
BBT: Basal Body Temperature
DPO: Days Past Ovulation
LP: Lutheal Phase
OD: Ovulation Day
AF: Aunt Flow (a.k.a. menstruation)
IB: Implantation Bleeding
BFP: Big Fat Positive (i.e. positive pregnancy test)
BFN: Big Fat Negative (i.e. negative pregnancy test)
POAS: Pee On A Stick (pregnancy test)
HPT: Home Pregnancy Test
PT: Pregnancy Test
FMU: First Morning Urine
BCP: Birth Control Pill
hCG: Human Chorionic Gonadotropin (i.e. hormone that tells your PT that's you're preggo)
EPT: Early Pregnancy Test
DS: Darling Son
DD: Darling Daughter
DH: Darling Husband
DB: Darling Boyfriend
DW: Darling Wife
TWW: Two Weeks Wait
FRER: First Response Early Result (pregnancy test)
OPK: Ovulation Prediction Kit (or Other People's Kids)
UTI: Urinary Tract Infection (some women mistake the frequent peeing you get with this for pregnancy)
PP: Pre/Past Pregnancy
Evap: Evaporading (i.e. false reading on HPT)
IUI: Intrauterine Insemination (Artificial Insemination)
IVF: In Vitro Fertalization (Egg meets sperm outside the female body, embryo is placed back in the woman)