Conception happens only near the time of ovulation. The number of fertile days in each cycle is not known, but there are many signs of ovulation which can be used to know when ovulation is happening.
The most precise sign is detection of Luteinizing Hormone (LH). It is released by the pituitary gland when the egg is mature. It causes the release of the egg.
What are signs of ovulation?
1. Positive LH test on OPK, showing the LH surge. This is a good predictor of ovulation.
2. Change in vaginal discharge. You may have clear and stretchy cervical fluid before ovulation (not on chart).
3. Higher body temperature at rest (BBT) after ovulation.
4. Progesterone hormone is made by corpus luteum after ovulation. It peaks 1 week after ovulation.
5. Ultrasound of ovaries shows follicles large enough to ovulate.
6. Menstrual period starts 2 weeks after ovulation.
The Ovulatory Cycle
Gonadotropin-releasing hormone (GnRH) is released in the hypothalamus at the base of the brain. GnRH is needed to start the cycle.
GnRH is carried to the pituitary where it stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH start the development of the ovarian follicle, which has the egg.
FSH acts on the ovary to keep the follicle growing and developing. FSH causes the follicle to make estrogen. Estrogen causes a mid-cycle LH surge to stimulate ovulation. The follicle ruptures and the egg is released.
The follicle becomes the corpus luteum and makes progesterone. This gets the endometrium ready for implantation of a fertilized egg (also known as an embryo).
These are on the upper part of the uterus. The tubes pick up the egg after leaves the ovary. After fertilization, the tube moves the fertilized egg into the uterus.
The fertilized egg implants in the uterus and develops throughout the pregnancy until the baby is born.
The egg survives 12 to 24 hours after ovulation. Sperm lives in the body 2 to 4 days. So, you may have up to a 4 to 5-day window to conceive.
Day 1 of a cycle is the first day of your period.
Ovulation may change from cycle to cycle. Many fertile persons will not ovulate on day 14. A person with a 28 to 30-day cycle will ovulate day 14 to 16. If ovulation is later, the cycle will be longer. A period usually happens 14 days after ovulation if you are not pregnant.
Our preferred kit is the Clearblue Digital Ovulation test.
- It is a very user-friendly kit for IUI timing.
- Ovulation occurs within 36 hours of noting a “smiley face” on the kit. This indicates an LH surge
- Look for the box that says “find your 2 peak days”
There are many other types of kits and trackers available. If not doing IUI you are welcome to use these, but please know that we are not always able to interpret the results.
The use of apps can be informative and helpful in learning more about your bodies’ patterns. However, they are based on averages and not always reliable, so please use OPKs in addition to confirm ovulation.
OPK Use and Timing
OPKs test urine for LH. Ovulation happens within 36 hours of the first hormone release. The purpose of OPK testing is to time intercourse or IUI procedures.
- Start testing day 11 of a cycle. Day 1 is the 1st day of heavy bleeding.
- Do not test before day 11. Fertility drugs (like Clomid) may give a false positive result if you test early.
- Test 1 time each day at about the same time of day.
- For the best IUI timing, do not test the first morning urine. Ignore kit instructions. Test during the day. Call the clinic by 3:30 p.m. to schedule IUI for the next day if you test is positive.
- If timing intercourse, have sex on the day of the positive result and the next day.
- Call the clinic if you do not have a positive result by day 22. Your progesterone blood level will be tested. This will help your care team know more about your cycle and plan for future cycles.
- The Center for Advanced Reproductive Care at 319-356-1767 Monday through Friday from 8 a.m. to 4:30 p.m.
- For urgent questions or concerns
- Call the Hospital Operator at 319-356-1616 on nights, weekends, and holidays.
- Ask for the gynecology resident on call.
- Toll-free at 800-777-8442, 24 hours a day
- Ask for the gynecology resident on call.
- You may be asked some questions when using the toll-free number.
Send a MyChart message for non-urgent questions or concerns.