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TWW, IVF, IDK: The Ultimate Guide To Fertility Acronyms

The language of infertility can be confusing! Let's explore some of the most common fertility acronyms and terminology.

March 12th, 2024 | 13 min. read

By Sierra Dehmler

When you enter the fertility world, you're forced to learn an entirely new language in order to understand your results, advocate for yourself, and communicate with your team. While it's an important part of the process, it can also feel daunting. Here's a crash course to help you feel more empowered.

In this article:

The Language of Infertility 

Trying to understand fertility lingo can feel a bit like stepping into a foreign land. And when you're already overwhelmed about your next steps towards becoming a parent or protecting your future fertility, adding a whole new dictionary of terms, abbreviations, and acronyms to your brain can be an added stressor.

That's why we're here to help you crack the code to the language of infertility! Each section below dives into a specific phase of the fertility or family-building process to define the most commonly used terms and help you understand what lies ahead.

Why is knowing these terms so helpful?

Becoming "fluent" in fertility speak helps you communicate more easily with your Care Team, advocate for yourself, and feel more confident during each step of the process.

When you're already taking in so much new information, having the vocabulary to ask the right questions and understand answers from your physician, nurse, and other team members can make a big difference. 

Remember: Your team will always be happy to explain these terms when needed if you forget what they mean, so don't be afraid to ask for clarification. They're there to help!

Preconception Terms

Trying to Conceive (TTC)

A term commonly used by the fertility community at large (both by those pursuing fertility treatment and those attempting pregnancy on their own) to describe focused efforts to conceive a baby. 

Semen Analysis (SA)

Examination of male ejaculate under a microscope to determine the number of sperm, their ability to move forward (motility) and their shape (morphology).

Semen analysis is an essential part of fertility testing, particularly in couples experiencing infertility. Sperm count, motility and morphology all provide important information about how the sperm will perform in treatment cycles.

Basal Body Temperature (BBT)

This is your body's temperature at rest which can be taken each morning before getting out of bed. BBT is measured orally each morning and recorded on a calendar chart. These charts can help identify the time of ovulation in people with regular cycles. 

Ovulation Predictor Kit (OPK)

An OPK is a home test that checks your urine to predict when you're most likely to be fertile. When your body is preparing to ovulate (release an egg), it produces more luteinizing hormone (LH) which is what OPKs detect.

Note: If you have a condition such as PCOS, it's important to know that OPKs test urine for a surge in luteinizing hormone (LH), which increases as you approach ovulation. Many PCOS patients have high levels of LH, which could falsely indicate ovulation. The bottom line - getting bloodwork done is the most accurate way to track ovulation.

Birth Control Pill (BCP)

A daily medication containing hormones that prevent pregnancy. Also used during fertility treatment cycles. In the video below, Nurse Practitioner Monica Moore explains why we use BCPs for patients who are trying to conceive (we know it can be confusing).

Fertility Testing Terms

Anti-Mullerian Hormone (AMH)

A hormone that corresponds to egg count and can help predict your current egg reserves. 

Follicle Stimulating Hormone (FSH)

A hormone produced by the pituitary gland that plays an important role in sexual development and functioning. In women, FSH helps control the menstrual cycle and stimulates the growth of eggs in the ovaries.

Thyroid Stimulating Hormone (TSH)

A hormone that stimulates the production of two main hormones (T3 and T4) and promotes healthy endocrine system function. An optimal TSH level is important for fertility, as these hormones affect ovulation.

Estradiol (E2)

One of the four types of estrogen produced mainly by the ovaries. The adrenal glands, placenta, testes, and some tissues also produce smaller amounts of this hormone. Often measured during fertility testing and treatment.

Hysterosalpingogram (HSG)

An X-ray procedure that detects whether the fallopian tubes are patent (open) or not, in order to determine if the tubes are blocking sperm from reaching ovulated eggs through the fallopian tubes. Special X-ray dye is gently injected through the uterus, then x-ray images are taken to see where the dye travels.

Note: Learn more about HSGs with our "What to Expect" guide.

Saline Infusion Sonohysterogram (SIS or SHG)

Saline infusion sonohysterography (SIS or SHG) is a procedure to evaluate the state of the uterus and shape of the uterine cavity, and detect any abnormalities. Using ultrasound and sterile saline fluid, the uterus and uterine lining are closely examined to ensure the environment is healthy and optimal for a future pregnancy.

Note: Learn more about SHGs with our "What to Expect" guide.

Endometrial Receptivity Analysis (ERA)

A special test performed during some IVF cycles to help determine whether the endometrium is receiving an embryo at the right time in an attempt to maximize chances of a successful pregnancy and live birth.

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Genetic & Embryo Testing Terms

Preimplantation Genetic Testing (PGT)

A technique for identifying genetic or chromosomal information about embryos before transferring them into the uterus to achieve a pregnancy. There are three different types of PGT (see below). Learn more about PGT here.

Note: PGT is different from genetic carrier testing, which is performed on the intended parents to screen for genetically-inherited disorders or chromosomal abnormalities.

Preimplantation Genetic Testing for Aneuploidies (PGT-A)

PGT-A identifies aneuploidy, the term used to describe any embryo with either too many or too few chromosomes (or large extra or missing pieces of chromosomes). One form of aneuploidy causes Down Syndrome, and other chromosomal changes may cause up to 60% of miscarriages or prevent pregnancy altogether.

Preimplantation Genetic Testing for Monogenic/Single-Gene Disorders (PGT-M)

PGT-M tests for monogenic (single gene) disorders, such as Cystic Fibrosis, Huntington’s disease, Sickle Cell Anemia, muscular dystrophy, and hemophilia – detection that is especially important for people who know their families carry the defective gene.

Preimplantation Genetic Testing for Chromosomal Structural Rearrangements (PGT-SR)

PGT-SR looks for structural rearrangements when a parent is known to carry a chromosome change such as a translocation or inversion. These can cause extra or missing chromosomal material in embryos.

Fertility Treatment Terms

Assisted Reproductive Technology (ART)

ART includes all clinical and laboratory treatments in which either eggs or embryos are handled with the intent to result in a pregnancy (for example, IUI and IVF).

Intracytoplasmic Sperm Injection (ICSI)

Placement of a single sperm into a single oocyte (egg) by penetrating the outer coating of the egg. This technique is used in cases with low sperm count, motility or morphology. ICSI is also used for patients who have had previous IVF cycles with failed fertilization.

Testicular/Epididymal Sperm Aspiration (TESA)

The surgical removal of sperm directly from the testes or the epididymis using a needle for aspiration. This procedure is used for men who have no sperm in their ejaculate or have had vasectomies in the past.

Sperm obtained through TESE requires ICSI to ensure fertilization of the oocyte (egg).

Vaginal Oocyte Retrieval (VOR)

The medical term for an egg retrieval during an IVF cycle.

Note: Learn more about the egg retrieval procedure with our "What to Expect" guide.

Ovarian Hyperstimulation Syndrome (OHSS)

A potential side effect of taking fertility medication during an IVF treatment cycle. Learn more about OHSS here.

Intrauterine Insemination (IUI)

IUI is a technique that transfers sperm directly into the uterus, bypassing the vaginal and cervical defense mechanisms of the female reproductive tract to allow for better sperm delivery to the fallopian tubes. 

Learn more: Get your comprehensive guide to IUI treatment here!

In Vitro Fertilization (IVF)

A common fertility treatment method that involves stimulating the ovaries to produce a large number of follicles, an egg retrieval procedure, fertilization of those eggs with designated sperm in the lab, embryo growth monitoring, and embryo transfer once the intended parents are ready to attempt pregnancy.

Learn more: Explore IVF treatment with this step-by-step guide from a fertility nurse.

Assisted Hatching (AH)

Assisted hatching is a procedure used in IVF treatment that can help the embryo “hatch” from its “shell” by creating a small crack in the zona pellucida (the transparent membrane surrounding the egg).

It is believed that assisted hatching can help an embryo implant in the uterus, leading to higher pregnancy rates in some patients.

Reciprocal In Vitro Fertilization (RIVF)

This treatment method is similar to traditional IVF, except that one female partner's eggs are retrieved and fertilized, with the resulting embryos being transferred into the second female partner to attempt pregnancy.

Explore other LGBTQ+ family-building options and resources for your journey with our resource hub, Gay Parents To Be or read one couple's RIVF story here.

Elective Single Embryo Transfer (ESET)

The process of only transferring one embryo into the uterus (versus transferring multiple embryos at once). It is now considered best practice in IVF treatment to only transfer one embryo at a time to ensure the safest pregnancy possible and best outcome for baby. 

Gestational Carrier (GC)

Also referred to as a gestational surrogate (or simply a surrogate), a gestational carrier is a woman who carries and delivers a child for another couple or individual (the intended parents). When using a GC, the eggs used to create the embryos come from a different egg donor source, not the GC.

Learn more: Read Tim & Steve's surrogacy story to hear about working with a GC.

Frozen Embryo Transfer (FET)

An embryo transfer using frozen embryos that have been thawed from a previous IVF cycle.

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Pregnancy-Related Terms

Human Chorionic Gonadotropin (hCG)

A hormone produced by the placenta during pregnancy which helps thicken the uterine lining to support a growing embryo. hCG levels rise after conception and continue to do so until around 10 weeks of pregnancy.

Days Past Transfer (DPT)

The number of days after an embryo transfer in an IVF treatment cycle.

Two-Week Wait (TWW or 2WW)

The window of time between ovulation and a missed period when you're waiting to take a pregnancy test. This term is also frequently used to indicate the span of time between embryo transfer and your "official" pregnancy test bloodwork at your fertility clinic (though it won't be a full two weeks - usually around 9-10 days after transfer). 

Get support for navigating the two-week wait from Brigitte, one of our fertility nurses.

Last Menstrual Period (LMP)

The first day (onset of full flow bleeding) of your last menstrual period before becoming pregnant.

Estimated Due Date (EDD)

The estimated date of delivery calculated based on conception date.

Dilation & Curettage (D&C)

A surgical procedure in which the cervix is dilated (expanded) so that the uterine lining can be scraped with a curette (spoon-shaped instrument) to remove abnormal tissue or remnants from a miscarriage.

Learn more about the D&C procedure with this guide.

General Fertility-Related Terms

Polycystic Ovary Syndrome (PCOS)

A common endocrine disorder that causes hormonal imbalances in women of reproductive age. It can lead to dysfunctional ovulation, fertility issues, weight gain, insulin resistance (pre-diabetes) and an increase in the male hormone, testosterone. 

Diminished Ovarian Reserve (DOR)

A condition in which the ovaries lose their normal reproductive potential, leading to reduced fertility and an increase in trouble getting pregnant due to a loss of quality and/or quantity eggs available for fertilization.

10-30% of patients presenting to doctors with infertility struggle with DOR.

Read about one woman's journey with DOR to learn more.

Luteinizing Hormone (LH)

A hormone made by the pituitary gland that plays an important role in sexual development and functioning. In women, LH helps control the menstrual cycle and trigger the release of an egg from the ovary. In men, LH causes the testicles to make testosterone, which is important for producing sperm. 

Luteal Phase Deficiency (LPD)

Also called luteal phase defect, LPD is a deficiency of progesterone in the second half of the menstrual cycle which can lead to issues conceiving. Treatment involves supplementation with progesterone and other measures.

Want to learn even more? Explore RESOLVE's Fertility Acronyms dictionary.

5 Tips for Your Next Appointment

It can be overwhelming being bombarded with new words, treatment options, and terminology during an appointment. Here are some ways to make your next appointment a little more efficient and manageable:

  • Take a notepad with you to jot down answers or follow-up questions
  • Prepare ahead of time and bring a list of questions with you
  • Ask your doctor to slow down or repeat something if needed
  • Have someone you trust attend the appointment with you and be a second pair of ears
  • Email or call your Care Team after the appointment for further clarification

Get Support From Our Patient Advocate

Illume Fertility offers free, one-on-one fertility support via our Patient Advocate, Lisa Rosenthal, who is a former fertility patient herself. You don't even need to be an Illume patient!

If you're having a difficult time communicating with your Care Team, have concerns about your treatment or are experiencing other challenges related to family building, reach out to Lisa at 203-354-1157 or email

Still feeling confused?

Don't be afraid to reach out to your Care Team at any time for clarification or ask your doctor to repeat or define terms you don't understand. Your team wants you to feel confident and comfortable with the information you're receiving.

You deserve to feel as empowered and confident as possible!

As you move through your fertility journey, you'll become more and more knowledgable, learning more terms, abbreviations and acronyms as you go.

While no one wants to be a pro when it comes to infertility (let's be honest - no one even wants to have to learn what these terms mean), becoming familiar with all of this information can help you feel more in control and prepared.

Sierra Dehmler

Sierra Dehmler is Illume Fertility’s Content Marketing Manager - and also a fertility patient herself. Combining empathy gained on her personal journey with her professional experience in marketing and content creation, she aims to empower and support other fertility patients by demystifying the fertility treatment process.

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