In Vitro Fertilization: An Overview

Infertility affects women and men. Sometimes the cause involves one partner. In other cases, it involves both partners. 

You're more likely to have infertility if you:

• Are in your late 30s or older
• Were exposed to toxic substances like lead or chemicals
• Exercise very intensely
• Have obesity or are underweight
• Have changes to your reproductive organs (uterus, fallopian tubes, scrotum, or testicles)
• Have an eating disorder like anorexia or bulimia
• Get few or no periods
• Smoke or have a substance use disorder
• Had a lot of heat exposure to your testicles from hot tubs, laptops, or tight pants
• Had radiation therapy or chemotherapy
• Drink excess amounts of alcohol

These conditions may increase your risk of infertility:

• Endometriosis
• Sexually transmitted infections (STIs) such as chlamydia, gonorrhea, or HIV
• Autoimmune diseases like lupus or celiac disease
• Pelvic inflammatory disease (PID)
• Polycystic ovary syndrome (PCOS)
• Primary ovarian insufficiency (POI) – when the ovaries stop working before age 40
• Chromosomal disorders such as Klinefelter syndrome
• Uterine fibroids or polyps
• Pituitary gland disorders
• Genetic disorders such as cystic fibrosis
• Low testosterone, called hypogonadism
• Thyroid disease 
• Sickle cell anemia

IVF Uses

Your fertility specialist might recommend IVF if you:

• Have damage or a blockage in your fallopian tubes
• Don't ovulate
• Have a low sperm count or a problem with sperm movement
• Can't get pregnant because of a condition like endometriosis or uterine fibroids
• Don't produce enough eggs or any eggs because of your age or POI
• Want to preserve your fertility before cancer treatment
• Have a genetic disorder that you don't want to pass to your child
• Had tubal ligation surgery to prevent pregnancy
• Want to have children at a later time

IVF is safe for most people. But your doctor might not recommend this procedure if you have a condition that makes pregnancy risky for you or your growing baby, such as:

• A serious heart condition such as late-stage heart failure, severely narrow valves (stenosis), a narrowed aorta, or Eisenmenger syndrome
• A genetic disorder such as Marfan syndrome
• Pulmonary hypertension – high blood pressure in the arteries of the lungs

Types of IVF

IVF is done in a few different ways.

Standard IVF vs. intracytoplasmic sperm injection (ICSI)

In standard IVF, a lab puts 50,000 to 100,000 sperm and an egg into a dish. The sperm fertilize the egg without help.

In ICSI, the fertility provider injects a single live sperm into the middle of an egg to create an embryo. Doctors use ICSI when the male partner has a low sperm count or low-quality sperm.

Frozen embryo transfer (FET)

This procedure is for people who froze their embryos because of a medical condition or to delay starting a family. During FET, the doctor thaws the embryos and places them into your uterus at the optimal time in your menstrual cycle. You might take hormones before this procedure to increase your chance of a pregnancy.

Donor egg IVF

Egg donation could be an option if you can't get pregnant because you have too few eggs or low-quality eggs. Same-sex couples may also choose to have a donor egg. The fertility clinic fertilizes the donor's egg with your partner's sperm and then implants the embryo into your uterus.

Donor embryo transfer 

Stages of IVF

IVF is a complex process that involves five steps:

Step 1: Ovarian stimulation

Normally, only one egg matures each month. During IVF, you take medicine to stimulate your ovaries so that several eggs mature each cycle. 

Your doctor will do ultrasounds and blood tests to see how the follicles in your ovaries are growing. Follicles are the sacs where eggs develop. In the final stage when your eggs are almost ready, you'll get a trigger shot of a hormone to prepare them for retrieval. 

Step 2: Egg retrieval

This procedure happens 36 hours after your trigger shot. Using ultrasound as a guide, your doctor inserts a needle into your uterus. A device attached to the needle pulls eggs out of your ovarian follicles. The eggs go into a dish, where they incubate until they are ready for fertilization.

Step 3: Fertilization

A specialist called an embryologist fertilizes all the mature eggs with standard insemination or ICSI. On average, about 7 out of every 10 eggs will fertilize. 

Step 4: Embryo culture

The embryos that form grow in a culture dish for five to seven days until they reach the blastocyst stage. A blastocyst is a ball of about 100 to 200 cells. The embryologist and fertility specialist decide which embryos are ready to implant.

Step 5: Embryo transfer

This procedure takes less than 10 minutes and shouldn't be painful. Using an ultrasound as a guide, the doctor places a soft tube called a catheter through your vagina and cervix into your uterus. Then they inject the embryos through the catheter.

In the early days of IVF, doctors would implant up to four embryos at a time to increase the odds of a pregnancy. Implanting more embryos also increases the chance of a multiple pregnancy like twins or triplets. Multiple pregnancies come with risks like preterm birth, cesarean section delivery, and birth defects. These days, if you are 37 or younger, your doctor will probably transfer only one good-quality embryo at a time. Having only one embryo boosts the odds of a live birth without increasing your risk of having multiples.

What Happens After Embryo Transfer

After the transfer, the blastocyst attaches to the lining of the uterus. It implants by day five. Levels of human chorionic gonadotropin (hCG) – a hormone made by the placenta during pregnancy – in your blood start to rise. By day nine, a blood test can usually detect hCG and confirm the pregnancy.

Medications Used in IVF

Doctors prescribe these medicines to stimulate the ovaries and make them release mature eggs:

Gonadotropins

Follicle stimulating hormone (FSH) and luteinizing hormone (LH) are gonadotropins. They're human-made versions of hormones your body makes. FSH and LH stimulate many follicles in the ovaries to mature at once and produce more eggs. This increases the chance of a pregnancy.

Gonadotropin-releasing hormone (GnRH) agonists 

GnRH is a hormone your brain makes. It stimulates your ovaries to make LH and FSH. GnRH agonists like leuprolide (Lupron) stimulate your pituitary gland to release these hormones. Seven days later, they turn off LH and FSH production. This helps many eggs mature and prevents your ovaries from releasing those eggs too early.

GnRH antagonists 

Success Rates

Many things influence your odds of having a baby with IVF, including:

• Your age
• How long you have had infertility
• What caused the infertility
• Your body mass index (BMI)
• How many egg-containing follicles are in your ovaries
• How many times you've been pregnant
• Your partner's sperm count and quality
• Which fertility clinic you use
• The number of eggs the clinic collects
• The type of IVF the clinic uses
• The quality of the transferred embryos
• What day of your cycle the embryo transfer happened

As you get older, the number and quality of your eggs decline, which makes it harder to get pregnant with IVF. 

Many things affect your odds of getting pregnant with each cycle, including your age, weight, and whether you or your partner has a problem with their ovaries, uterus, or sperm. In general, someone age 30 who is 5' 4'' tall and weighs 125 pounds has a: 

• 63% chance of getting pregnant in the first cycle
• 81% chance of getting pregnant in the second cycle
• 89% chance of getting pregnant in the third cycle

Advances in IVF

This technology has come a long way since the birth of the first IVF baby in 1978. These are just some of the breakthroughs that are helping to improve the odds of an IVF pregnancy.

Preimplantation genetic testing (PGT)

PGT is a technology that screens embryos for abnormal genes before the doctor implants them. It may lower your risk of a miscarriage if you're over age 37 and prevent you from passing an inherited disease to your child.

Assisted hatching

When an embryo forms during IVF, it has a hard, egg shell-like outer coating called the zona pellucida. The embryo has to break out of this shell to implant in the uterus and grow. In assisted hatching, the embryologist makes a tiny hole in the zona pellucida with a laser to help the embryo implant.

Time-lapse imaging

Usually during IVF, an embryologist checks the growing embryos under a microscope to see which ones are most likely to develop into a baby. Time-lapse imaging combines a microscope with a camera that takes thousands of pictures of each embryo as it develops. Seeing the whole growth process makes it easier for the embryologist to choose the best ones to transfer. 

AI embryo selection

Artificial intelligence (AI) could help streamline the process of picking embryos to implant. AI may be more accurate at choosing embryos than embryologists, which might increase the chance of success. But because the technology is still new, studies need to confirm how well it works.

Improved freezing techniques

Fertility specialists freeze embryos in one of two ways: 

Slow freezing slowly cools the embryos in a special machine, then stores them in liquid nitrogen. 

Vitrification puts the embryos into a solution that protects them from cold damage. Then they go into liquid nitrogen to freeze. Embryos that are frozen using vitrification are more likely to survive after they thaw.