Walk into any trying-to-conceive community online, and you'll be hit with a wall of abbreviations. It's not gatekeeping—it's just shorthand that evolved organically as people shared their fertility journeys. Once you know the language, you'll feel right at home.
This glossary covers everything from basic TTC terms to medical abbreviations you might encounter at a fertility clinic. Bookmark this page—you'll come back to it.
🔥 Most Common Terms (Quick Reference)
TTC
Trying to Conceive
BFP
Big Fat Positive
BFN
Big Fat Negative
DPO
Days Past Ovulation
TWW
Two-Week Wait
OPK
Ovulation Predictor Kit
CD
Cycle Day
AF
Aunt Flo (Period)
BD
Baby Dance (Sex)
CM
Cervical Mucus
BBT
Basal Body Temp
LH
Luteinizing Hormone
A
AF
Aunt Flo
Slang term for your period/menstruation. The name probably started as a way to talk about periods discreetly.
"AF arrived this morning, so we're onto cycle 4."
AFC
Antral Follicle Count
An ultrasound measurement of the small follicles visible on your ovaries at the start of a cycle. It's used to estimate ovarian reserve—how many eggs you have remaining.
AMH
Anti-MĂĽllerian Hormone
A blood test that measures ovarian reserve. Higher levels generally indicate more eggs remaining; lower levels suggest diminished reserve. It's one indicator of fertility potential, especially used in IVF planning.
ART
Assisted Reproductive Technology
Medical procedures that handle eggs and/or sperm to help achieve pregnancy. Includes IVF, ICSI, and similar treatments. IUI is sometimes included, sometimes not, depending on the definition used.
B
BBT
Basal Body Temperature
Your body's lowest resting temperature, taken first thing in the morning before getting out of bed. BBT rises slightly (about 0.5°F) after ovulation due to progesterone, which can help confirm that ovulation occurred.
"My BBT spiked this morning, so I'm pretty sure I ovulated yesterday."
BD
Baby Dance
A cutesy euphemism for sex, specifically sex intended to make a baby. You'll see this constantly in TTC forums.
"We BD'd on O-2, O-1, and O day!"
BFN
Big Fat Negative
A negative pregnancy test result. The "big fat" part acknowledges the emotional weight of seeing that single line or "not pregnant" reading.
BFP
Big Fat Positive
A positive pregnancy test result! The goal everyone is working toward. Often shared in forums with cautious excitement.
"Got my BFP at 12 DPO! Can't believe it!"
BW
Bloodwork
Blood tests. In fertility contexts, this usually means hormone testing (FSH, LH, estrogen, progesterone, AMH, thyroid, etc.).
C
CD
Cycle Day
The day of your menstrual cycle, counting from the first day of your period. CD1 is the first day of full flow. CD14 is often assumed to be ovulation day in a "textbook" 28-day cycle (though ovulation timing varies).
"I'm on CD10 and starting to see fertile CM."
CM
Cervical Mucus
The mucus produced by your cervix that changes throughout your cycle. Tracking CM helps identify fertile days—fertile mucus is clear, stretchy, and slippery (like raw egg whites).
CP
Chemical Pregnancy
A very early pregnancy loss that occurs shortly after implantation. The pregnancy is "chemical" because it was detected only by a pregnancy test (measuring hCG), not by ultrasound. It's essentially a very early miscarriage.
D
DH
Dear Husband
Forum shorthand for husband or male partner. Part of a family of "dear" abbreviations (DP = Dear Partner, DW = Dear Wife, etc.).
DPO
Days Past Ovulation
How many days it's been since you ovulated. This is crucial for timing pregnancy tests—most tests are accurate by 12-14 DPO. You'll often see symptom discussions framed as "I'm 8 DPO and feeling..."
"I got a faint line at 10 DPO!"
DPT
Days Past Transfer
Used in IVF contexts—how many days since the embryo was transferred to the uterus. Pregnancy tests are usually taken around 9-14 DPT depending on embryo stage at transfer.
DOR
Diminished Ovarian Reserve
A diagnosis indicating lower-than-expected egg quantity for your age. Identified through AMH levels and AFC counts. It doesn't mean you can't conceive, but may affect treatment approaches.
E
E2
Estradiol (Estrogen)
The main form of estrogen. In fertility treatment, E2 levels are monitored to track follicle development. Rising E2 indicates growing follicles.
EDD
Estimated Due Date
The projected date when your baby would be born, calculated as 40 weeks from your last menstrual period (or adjusted based on ultrasound). Only about 5% of babies are born on their actual EDD.
EWCM
Egg White Cervical Mucus
The fertile-quality cervical mucus that resembles raw egg whites—clear, stretchy, and slippery. This is your body's sign that you're in or approaching your fertile window. EWCM helps sperm survive and travel.
"Finally got EWCM today! Time to BD."
ER
Egg Retrieval
The IVF procedure where eggs are collected from the ovaries using a needle guided by ultrasound. Usually done under sedation.
ET
Embryo Transfer
The IVF procedure where an embryo is placed into the uterus. Can be a fresh transfer (same cycle as retrieval) or frozen transfer (FET).
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F
FET
Frozen Embryo Transfer
An IVF embryo transfer using a previously frozen embryo rather than a fresh one. Often done in a later cycle after the body has recovered from egg retrieval.
FF
Fertility Friend
A popular fertility tracking app and website used for charting BBT, CM, and other fertility signs. "My FF chart shows..." is common in forums.
FMU
First Morning Urine
The first urine of the day, which is most concentrated. Pregnancy tests are often more sensitive when using FMU because hCG is more concentrated.
"Going to test with FMU tomorrow at 11 DPO."
FSH
Follicle Stimulating Hormone
A hormone that stimulates follicle growth in the ovaries. FSH levels measured on day 3 of your cycle can indicate ovarian reserve—higher levels may suggest the ovaries are working harder to produce eggs.
FW
Fertile Window
The approximately 6-day period each cycle when pregnancy is possible: the 5 days before ovulation plus ovulation day itself.
H
hCG
Human Chorionic Gonadotropin
The "pregnancy hormone" produced after implantation. Pregnancy tests work by detecting hCG. Levels rise rapidly in early pregnancy and can be tracked via blood tests to monitor pregnancy viability.
HPT
Home Pregnancy Test
A pregnancy test you take at home (vs. a blood test at a lab). These detect hCG in urine.
HSG
Hysterosalpingogram
An X-ray test where dye is injected into the uterus to check if the fallopian tubes are open and if the uterine cavity is normal. Often done as part of fertility workup.
I
IC
Internet Cheapie
Inexpensive pregnancy or ovulation tests bought in bulk online (like Wondfo, Easy@Home, or similar brands). Popular because you can test frequently without breaking the bank.
ICSI
Intracytoplasmic Sperm Injection
An IVF technique where a single sperm is injected directly into an egg. Used when sperm quality is a concern or standard IVF fertilization hasn't worked.
IUI
Intrauterine Insemination
A fertility treatment where washed, concentrated sperm is placed directly into the uterus around ovulation time. Less invasive and less expensive than IVF, often tried first.
IVF
In Vitro Fertilization
A fertility treatment where eggs are retrieved from the ovaries, fertilized with sperm in a laboratory, and resulting embryos are transferred to the uterus. The most advanced (and effective) form of fertility treatment.
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L
LH
Luteinizing Hormone
The hormone that surges 24-36 hours before ovulation. Ovulation predictor kits (OPKs) work by detecting this LH surge, telling you ovulation is about to happen.
LMP
Last Menstrual Period
The first day of your most recent period. Used as a starting point for pregnancy dating—your due date is calculated as 40 weeks from LMP.
LO
Little One
Forum slang for a child, either existing or hoped-for.
LP
Luteal Phase
The second half of your menstrual cycle, from ovulation until your period starts (or pregnancy begins). A healthy luteal phase is typically 10-16 days. Shorter than 10 days may indicate a "luteal phase defect."
LPD
Luteal Phase Defect
A condition where the luteal phase is too short (under 10 days) or progesterone production is insufficient, potentially making implantation difficult.
M
MC
Miscarriage
Pregnancy loss before 20 weeks. About 10-20% of known pregnancies end in miscarriage, with the actual rate (including very early losses) being higher.
MFI
Male Factor Infertility
Infertility caused or contributed to by male factors—low sperm count, poor motility, abnormal morphology, etc. Male factors are involved in about 40% of infertility cases.
MMC
Missed Miscarriage
A miscarriage where the embryo has stopped developing but hasn't been expelled from the body. Often discovered at an ultrasound when no heartbeat is found.
O
O
Ovulation
When an egg is released from the ovary. The term is also used in timing discussions: O-1 means one day before ovulation, O day is ovulation day, O+1 is one day after ovulation, etc.
"We hit O-2, O-1, and O day."
OB/OB-GYN
Obstetrician/Gynecologist
A doctor specializing in women's reproductive health, pregnancy, and childbirth. Your OB-GYN may do initial fertility evaluation before referring to a specialist (RE).
OPK
Ovulation Predictor Kit
Tests that detect the LH surge before ovulation. When the test line is as dark or darker than the control line, ovulation is likely within 24-36 hours.
OPSO
One Pink Second Opinion
Taking a second pregnancy test to confirm what you saw on the first (especially for faint lines). Forums often use this when someone posts a squinter.
P
PCOS
Polycystic Ovary Syndrome
A hormonal condition affecting 6-12% of women, characterized by irregular periods, excess androgens, and polycystic ovaries. A leading cause of ovulation problems and infertility, but very treatable.
PG
Pregnant
Short for pregnant. Sometimes written to be sensitive in TTC spaces where not everyone has achieved pregnancy yet.
PGT
Preimplantation Genetic Testing
Testing done on embryos during IVF to check for genetic abnormalities before transfer. PGT-A tests for chromosomal abnormalities; PGT-M tests for specific inherited conditions.
PIO
Progesterone in Oil
Injectable progesterone used for luteal phase support in IVF cycles. Given as intramuscular injections.
POAS
Pee on a Stick
Taking a pregnancy test or ovulation test. "POAS addict" is someone who tests very frequently.
R
RE
Reproductive Endocrinologist
A doctor who specializes in fertility and reproductive hormones. REs have additional training beyond OB-GYN and handle complex fertility cases, IUI, and IVF.
RPL
Recurrent Pregnancy Loss
Having two or more pregnancy losses. RPL warrants investigation into potential causes like genetic issues, uterine abnormalities, clotting disorders, or hormonal problems.
S
SA
Semen Analysis
A test evaluating sperm count, motility (movement), and morphology (shape). One of the first tests done in fertility workup since male factors are so common.
SI
Secondary Infertility
Difficulty conceiving or carrying a pregnancy after previously having a child without fertility treatment. It's more common than many realize.
SMEP
Sperm Meets Egg Plan
A popular intercourse timing strategy: start having sex every other day from cycle day 8, increase to daily when you get a positive OPK, continue for a few days after.
Squinter
(No abbreviation)
A very faint line on a pregnancy test that makes you squint to see it. Usually photographed and posted in forums with "Do you see what I see?"
T
TI
Timed Intercourse
Having sex at specific times relative to ovulation, often with medical monitoring. In fertility treatment, TI means having intercourse at home (vs. IUI or IVF) while taking fertility medications.
TTC
Trying to Conceive
The umbrella term for actively trying to get pregnant. The TTC community refers to people on this journey together.
TTCAL
Trying to Conceive After Loss
Trying to conceive after experiencing a miscarriage or other pregnancy loss. There are specific TTC communities for this difficult journey.
TWW
Two-Week Wait
The approximately two weeks between ovulation and when you can take a pregnancy test (or your period arrives). Known as the most anxiety-inducing part of the TTC cycle.
"I'm 5 DPO and the TWW is already driving me crazy."
U
UI
Unexplained Infertility
When fertility testing doesn't reveal an obvious cause for difficulty conceiving. About 10-30% of infertility cases are classified as unexplained. Treatment often still helps even without a clear diagnosis.
US/U/S
Ultrasound
Imaging using sound waves. In fertility, transvaginal ultrasounds monitor follicle development, check uterine lining, count antral follicles, and eventually see early pregnancy.
Unicorn
(No abbreviation)
Someone who gets pregnant on their first cycle trying. Called a "unicorn" because it seems rare and magical to those who struggle.
đź’ˇ Pro Tip: Context Clues
If you encounter an abbreviation you don't recognize, the surrounding context usually helps. "BFP at 12 DPO!" is clearly pregnancy-related even if you don't know the exact meanings. Don't be afraid to ask in forums—everyone was new once!
Ready to Start Tracking?
Now that you know the lingo, put it to use. Calculate your fertile window and join the TTC journey!
Ovulation Calculator →A Note on TTC Culture
TTC forums and communities can be wonderful sources of support, but they can also be overwhelming if you're new. The shared language creates camaraderie, but it can feel exclusionary at first.
A few tips for navigating TTC spaces:
Be mindful of triggers. Many people in TTC communities have experienced loss or are dealing with infertility. Sharing good news is welcome, but be sensitive in how you do it.
Take everything with a grain of salt. Forum advice isn't medical advice. What worked for someone else may not work for you. Consult your doctor for medical decisions.
It's okay to take breaks. Constant TTC discussion can become all-consuming. Stepping back from forums when it starts affecting your mental health is healthy.
Everyone's journey is different. Comparisons are inevitable but not always helpful. Your timeline is your timeline.
Welcome to the TTC community—now you speak the language!