If you have ever lurked in a fertility forum and felt like you needed a decoder ring to understand what anyone was saying, this glossary is for you. From clinical terms used by doctors to community shorthand used in forums, here is every fertility acronym decoded and explained.
Cycle and Tracking Acronyms
AF: Aunt Flo — colloquial term for menstruation. CD: Cycle Day — the day of your menstrual cycle, with CD1 being the first day of full flow. DPO: Days Past Ovulation — the number of days since ovulation occurred, used to track where you are in the luteal phase. BBT: Basal Body Temperature — the lowest body temperature in a 24-hour period, measured upon waking before any activity. BBT rises approximately 0.2°C after ovulation due to progesterone and is used to confirm that ovulation has occurred. OPK: Ovulation Predictor Kit — a urine test that detects the LH surge before ovulation. EWCM: Egg White Cervical Mucus — the stretchy, clear, fertile-quality cervical mucus that appears in the days before ovulation. TWW or 2WW: Two Week Wait — the luteal phase between ovulation and the expected period, during which pregnancy can be tested.
FF: Fertility Friend — a popular fertility tracking app. LP: Luteal Phase — the second half of the menstrual cycle from ovulation to menstruation. O or OV: Ovulation. LH: Luteinizing Hormone — the hormone that surges before ovulation and is detected by OPK strips. BFP: Big Fat Positive — a positive pregnancy test. BFN: Big Fat Negative — a negative pregnancy test. Dpo: see DPO above. WTO: Waiting To Ovulate — the period in the follicular phase waiting for the LH surge. BD: Baby Dancing — community shorthand for intercourse (used primarily in TTC communities where ICI is not the method). FW: Fertile Window.
Clinical and Medical Acronyms
RE: Reproductive Endocrinologist — a physician specializing in fertility and hormonal disorders of the reproductive system. ART: Assisted Reproductive Technology — umbrella term for medical procedures used to achieve pregnancy when natural conception is insufficient. ICI: Intracervical Insemination — placement of sperm near the cervical os. IUI: Intrauterine Insemination — placement of washed sperm directly in the uterine cavity. IVF: In Vitro Fertilization — egg retrieval, laboratory fertilization, and embryo transfer. ICSI: Intracytoplasmic Sperm Injection — a form of IVF in which a single sperm is injected directly into the egg. FET: Frozen Embryo Transfer — transfer of a thawed cryopreserved embryo.
AMH: Anti-Mullerian Hormone — a blood marker of ovarian reserve reflecting the remaining follicle pool. FSH: Follicle-Stimulating Hormone — the pituitary hormone that drives follicle development. AFC: Antral Follicle Count — ultrasound count of small follicles visible in the ovaries on cycle days 2–5. TSH: Thyroid-Stimulating Hormone — a thyroid health marker relevant to fertility. HSG: Hysterosalpingogram — an X-ray procedure using contrast dye to evaluate tubal patency and uterine cavity morphology. SIS or SHG: Saline Infusion Sonography / Sonohysterogram — ultrasound evaluation of the uterine cavity using saline contrast. SA: Semen Analysis — laboratory evaluation of sperm parameters. TMC: Total Motile Count — concentration multiplied by total motility multiplied by volume, the most useful single sperm parameter for ICI suitability. DFI: DNA Fragmentation Index — measure of DNA damage in sperm.
Protocol and Treatment Acronyms
hCG: Human Chorionic Gonadotropin — both the pregnancy hormone detected by pregnancy tests AND the name of the injection used to trigger ovulation in stimulated cycles. Trigger shot: the hCG injection that causes a mature follicle to rupture approximately 36–40 hours after administration. CC or Clomid: Clomiphene Citrate — an oral ovulation induction medication. Letrozole or Femara: an aromatase inhibitor used as the preferred first-line ovulation induction agent due to superior results and fewer side effects than clomiphene. PGT-A: Preimplantation Genetic Testing for Aneuploidy — genetic screening of IVF embryos before transfer to select chromosomally normal embryos. PIO: Progesterone in Oil — injectable progesterone used for luteal phase support in IVF cycles. P4: Progesterone — a luteal phase hormone, tested midluteal to confirm ovulation.
ER: Egg Retrieval — the transvaginal procedure in IVF cycles to collect mature eggs from the ovaries. ET: Embryo Transfer — the procedure that places embryo(s) into the uterus. OHSS: Ovarian Hyperstimulation Syndrome — a potentially serious complication of ovarian stimulation characterized by enlarged ovaries and fluid accumulation. Stims: gonadotropin stimulation medications used in IVF and some IUI protocols to develop multiple follicles. Blastocyst: an embryo at day 5–6 of development, the preferred stage for transfer and genetic testing. Morula: an embryo at day 4. PGS: outdated term now replaced by PGT-A. ERA: Endometrial Receptivity Array — a biopsy-based test assessing the optimal implantation window timing for a specific patient.
Community and Forum Acronyms
TTC: Trying to Conceive. SMC: Single Mother by Choice — a woman pursuing parenthood without a co-parenting partner. SMBC: Single Mother By Choice (variant). LGBTQ+: Lesbian, Gay, Bisexual, Transgender, Queer/Questioning, and more — used in fertility contexts to refer to LGBTQ+ family-building. KD: Known Donor — a known sperm donor as opposed to an anonymous bank donor. DIY: Do It Yourself — home-based insemination as opposed to clinic-based. SD: Sperm Donor. CD: Can mean either Cycle Day (context: CD14, meaning cycle day 14) or Conception Donor (context: ‘using a CD’). DH: Dear Husband. DW: Dear Wife. DP: Dear Partner. SO: Significant Other.
RPL: Recurrent Pregnancy Loss — typically defined as three or more pregnancy losses before 20 weeks. CP: Chemical Pregnancy — a very early pregnancy loss, typically detected only by a sensitive pregnancy test before clinical confirmation. MC: Miscarriage — pregnancy loss before 20 weeks gestation. PCOS: Polycystic Ovary Syndrome — the most common ovulatory disorder, characterized by irregular ovulation, elevated androgens, and/or polycystic ovarian morphology. Endo: Endometriosis. MFI: Male Factor Infertility. DOR: Diminished Ovarian Reserve. POI: Premature Ovarian Insufficiency (previously called premature ovarian failure). POAS: Pee on a Stick — informal term for taking a home pregnancy or ovulation test. POAS addict: community shorthand for testing more frequently than recommended.
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Further reading across our network: MakeAmom.com · Mosie.baby · IntracervicalInseminationKit.info · IntracervicalInsemination.com
This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before making decisions about your fertility care.