Fertility Basics: What to Know Before You Start Trying

Isla Oliver, DNP, CNM, ARNP

Understanding Fertility: A Guide for Women and Gender-Diverse Individuals in Washington State

We receive a lot of messaging from a very young age about how to prevent pregnancy. This is very helpful for a long time, but it often leaves people floundering when they are ready to start a family and realize that it might not actually be as easy as they were led to believe.

How do I know if I'm fertile?

There are a few common signs of normal fertility that you can look for. First, is regular periods. Clinically, a typical adult menstrual cycle runs 21–34 days, with cycles considered regular if they don't vary by more than about a week from one to the next.¹ When we talk about the spacing between periods, we're talking about the time from the first day of bleeding (spotting counts) of one period to the first day of bleeding of the next.

Periods can differ in length — most people bleed for 2–7 days¹ — and amount of blood, from spotting to heavy, and still be considered normal. Blood clots during your period are also considered a normal function of uterine cramping, as long as they are smaller than a lime.

Next, those dreaded PMS symptoms. While no one likes dealing with premenstrual syndrome, the hormonal changes you see — breast tenderness, moodiness, acne, even headaches — are all a good sign that your body made and released an ova (egg) that month. The exact mechanism is complex and not fully understood, but PMS symptoms are thought to result from progesterone's effects on brain chemicals like GABA, serotonin, and other neurotransmitters², and that progesterone comes from the corpus luteum, which forms after ovulation and degrades if no pregnancy occurs — driving the hormone shifts that cause PMS.

Finally, ovulation tracking. You can track ovulation in many ways, but for everyone who is ovulating, it will occur 12–14 days before your period. We measure backwards from your period because this is how long it takes a corpus luteum to break down, and that breakdown is what causes your period to happen. Since this time frame is reliable, if you have 28-day cycles, ovulation will occur around day 14, but if you have 35-day cycles, it will happen closer to day 21. Tracking ovulation is all about pattern recognition over time.

You can also track ovulation using ovulation predictor (LH) strips, by checking your cervical mucous (vaginal discharge) throughout the month, and by tracking your basal body temperature. Johns Hopkins Medicine has a helpful explanation of how each of these methods works.³

In general, if you are having regular periods and showing signs of ovulation, we assume you are fertile and there is no testing necessary for otherwise healthy people.

When can I get pregnant?

This is the part that most people are misled on in adolescence. Were you told "you could get pregnant any day of the month, even on your period"? Because I was. While this may be true in immature adolescent bodies which are having random 14–40 day cycles and are still regulating, it is not the case for most adults with regular periods.

We know that you ovulate 12–14 days before your period, and that sperm ejaculated into the vagina reaches the fallopian tubes within minutes, and can survive there for several days. The American Society for Reproductive Medicine defines the fertile window as the six-day window ending on the day of ovulation.⁴ Based on this, we can calculate your fertile window in the 5 days leading up to ovulation.

Let's take the example of a 28-day cycle again — if you typically ovulate on day 14–16, sex occurring days 9–16 could result in a pregnancy.

If your cycle is 35 days — ovulation occurs between days 21–23, sex on days 16–23 could result in a pregnancy.

ASRM's patient guidance recommends intercourse every one to two days during the fertile window for the best chance of pregnancy, and notes that long periods of abstinence can actually decrease sperm quality — so there's no benefit to “saving up.”⁴ Sperm motility and quality are optimized when that person is ejaculating every 1–2 days, or at least every 3 days throughout the month.⁵

You get to decide if you want to be part of that particular endeavor or not!

What else should I be doing?

During conception and prior to pregnancy, it's important to think about several lifestyle factors that can impact fertility and early pregnancy.

1. Take a prenatal vitamin — There are certain nutrients, like folic acid, that are very important in the first few weeks of pregnancy, before most people know they are pregnant. The CDC recommends all people capable of becoming pregnant get 400 micrograms of folic acid daily to help prevent neural tube defects,⁶ so we recommend prenatal vitamins as soon as you decide to try to conceive. They can be expensive, so if you can't do a full prenatal, I recommend at least 800mcg of folic acid daily. I strongly recommend against beef organ supplements like Primal Queen as an alternative — clinically, I have seen many people have significant side effects from this type of supplement, and they often don't contain enough folic acid.

2. Cut out alcohol, tobacco, and marijuana — I recommend both you and your partner stop drinking alcohol, smoking tobacco, or using marijuana. We know there are several pregnancy complications strongly linked to the health of the sperm-carrying partner — things like nausea, hyperemesis (excessive vomiting), preeclampsia, and possibly even preterm birth.^7,8 This is all the more reason for you both to be engaging in the kind of healthy lifestyle changes that would be necessary for the gestating partner once they are pregnant. And yes, unfortunately, we are learning more and more that marijuana use does seem to negatively impact pregnancy and the growing fetus.⁹

3. Establish healthy routines now — "I'll start working out when…" "I'll eat better when…" We all put things off, and these are common thoughts people have when planning for their family. This advice is simple: it is so much easier to form these types of habits when you are not tired, hungry, stressed, or feeling the emotional toll of a pregnancy. If you think you should be incorporating more exercise, vegetables, or other dietary changes or even stress-reduction strategies into your life, I recommend starting early so that it feels like second nature by the time pregnancy does happen.

4. Check your immunity — As people are having children later in life, we are seeing higher rates of waning immunity to diseases like measles, mumps, and rubella — diseases that your baby will rely on your immunity to protect them from. It is not uncommon to see people lose immunity around age 30 to one or more of these diseases. MMR is a live vaccine that's contraindicated during pregnancy, and the CDC advises avoiding pregnancy for 28 days after getting it,¹⁰ which is why it needs to happen before you start trying. I recommend requesting a titer to check your immunity at the start of your conception journey.

How do I know if something is wrong?

It's important to keep in mind that it is normal for conception to take many months. Again, this can feel like it goes against everything we were ever taught, but we only get a chance once a month if we're lucky, so give your incredible body some grace. Creating an entire human can take some time.

Reasons to follow up with your provider include:

1. If you are not seeing signs of ovulation, or not having monthly periods.

2. If you are under age 35 and have been trying with timed intercourse during your fertile window for 12 months.

3. If you are 35 and over and have been trying with timed intercourse during your fertile window for 6 months.

4. If you just have questions or need guidance beyond what the internet can provide.

This matches ASRM's clinical guidance: evaluation should begin at 12 months of trying for women under 35, and at 6 months for women 35 and older.¹¹ In these cases, your provider might recommend labs or imaging, or might be able to coach you on best practices for tracking your menstrual cycle. In some cases, they might recommend medication to stimulate ovulation.

When it comes to learning about conception, it can feel like there's a whole new language to take on. But please know you are not alone! We are always happy to see you for preconception counseling — and know that the more we talk about it, the more we all get to learn.

Sources

1. American College of Obstetricians and Gynecologists (ACOG). Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign. Committee Opinion No. 651. acog.org

2. StatPearls (NCBI Bookshelf). Premenstrual Syndrome. ncbi.nlm.nih.gov

3. Johns Hopkins Medicine. Calculating Your Monthly Fertility Window. hopkinsmedicine.org

4. American Society for Reproductive Medicine (ASRM). Optimizing Natural Fertility — Patient Fact Sheet. reproductivefacts.org

5. National Center for Biotechnology Information. pmc.ncbi.nlm.nih.gov

6. Centers for Disease Control and Prevention (CDC). Folic Acid: Facts for Clinicians. cdc.gov

7. National Center for Biotechnology Information. pmc.ncbi.nlm.nih.gov

8. National Center for Biotechnology Information. pmc.ncbi.nlm.nih.gov

9. American College of Obstetricians and Gynecologists (ACOG). What I Tell My Patients About Marijuana Use During Pregnancy. acog.org

10. Centers for Disease Control and Prevention (CDC). Guidelines for Vaccinating Pregnant Women. cdc.gov

11. American Society for Reproductive Medicine (ASRM). Definition of Infertility: A Committee Opinion (2023). asrm.org