Sex Education for Parents and Teens, Part I: Human Reproductive Biology Basics

Oct 14

How to get girls off to a healthy start

By David Siegel

Sex education is offered in many schools, but don't count on classroom instruction alone. Sex education needs to happen at home too.
- Mayo Clinic

When I was 20, I took a class on human sex taught by an amazing professor. I became his teaching assistant. Since then, I’ve spent a lot of time learning about human reproductive biology. And I see a huge gap between what kids know and what they should know. I’m not an expert. I’m not a professional. The state of sex education in the United States is abysmal and getting worse. I teach a class to girls and their parents who ask me to do it, and I want to give that class here, so you can use it in your community.

This is a class for girls who have had at least 3 periods and their parents, with resources at the end. I’m giving it to you, in case you can use any of this information to help your conversations with children. Please use, modify, and share it.

A few caveats before we begin …

CAVEAT 1: Undoubtedly, people will misread or not-even read this and say negative things about me. Parents are protective of their girls, yet they don’t know the basics, and girls often say they don’t want to talk with their parents. People react without thinking.

CAVEAT 2: I’m not a licensed therapist or professional. What sex therapists do is often very difficult, and they don’t get paid much to do it. I’m glad they are here for those who need. But to get kids started when they are in their early teens, I don’t think most people need a therapist.

CAVEAT 3: Professionals can’t believe someone without a government-issued license is talking with teens about sex. But the US has one of the most uninformed populations in the world despite the regulations and licenses. In my view, the best solution for parents and teens is a combination of books, videos, articles, and conversations. There’s a lot of bad advice out there, but that’s always true, and people with licenses are not immune to being wrong.

CAVEAT 4: For medical or professional advice, seek a doctor or therapist. There are many good resources available (though thanks to the Supreme Court recently, there are fewer than there used to be).

CAVEAT 5: Don’t assume I’m 100 percent right about anything. I’m always trying to learn more. If I’ve gotten anything wrong, leave a comment or contact me via the form and I’ll work on it.

This is in six parts:

Human reproductive biology basics for girls
Birth control
Mechanics
Behavior
Social
Pregnancy and birth

This is just chapter 1. If there’s demand, I’ll put together the others, plus a chapter on human reproductive biology for boys (but I don’t think boys are nearly as interested)

Part 1: Human Reproductive Biology Basics

Introduction

At the beginning, I explain that there is a spectrum of sexual activity that is very broad, but I’m starting the class with sex between a woman and a man, because that’s how babies get born. Other topics will be covered later, and that’s not to belittle them in any way.

For the first ten minutes, there is an easy introduction and meet and talk with girls and parents to ask a few questions, get to know each other, see what they would like to learn, etc. Both girls and parents are usually embarrassed, often the parents are more embarrassed than the girls.

I gear the class toward the girls participating. 12-year-olds will be very different from 17-year-olds. Girls from progressive households are different from those with religious parents. Girls who are very socially active are different from introverts. Here I’m giving the basics, but it would be presented and discussed in a way that’s right for the girls and parents to get them to engage and talk. You’ll find that the girls are probably more advanced than you thought.

This class is generally taught in a ninety minute session with parents and girls together. The safer everyone feels, the more they can learn.

Both parents and girls start nervous and can become embarrassed as the conversation goes on. They may not want to admit things in front of the other. I say it’s fine to just stay quiet if you don’t want to talk. You should do whatever you’re comfortable with.

The most important message

The first thing all girls need to know is that they should not be in a rush to do things with boys. Everyone starts as a beginner. Almost no one ever becomes even an intermediate; parents are a good example. They don’t know how to facilitate a good conversation. They screwed it up themselves when it was their time, and the only thing they have now is more worries. Girls should take one step at a time, don’t take risks, and learn as much as they can. If you’re not comfortable with a situation, forget the peer pressure, forget who else is doing it, if it’s not right for you, don’t do it.

The gap in our knowledge

According to Statista:

35% of adult US women don’t know when a woman is most fertile.
31% don’t fully understand how their reproductive system works.
16% don’t understand menstruation.

According to a Planned Parenthood report:

Fewer than half of high schools and less than a fifth of middle schools teach all 20 topics recommended by the CDC as essential components of sex education.
Adolescents were less likely to report receiving sex education on key topics in 2015–2019 than they were in 1995.
Although almost every state has some guidance on how and when sex education should be taught, decisions are often left up to individual school districts, creating a patchwork of inconsistent policies and practices within states.

How many people are having sex?

I estimate that at any given time, between 1 and 2 million couples are having intercourse around the world. Because of birth control and many other factors, that leads to around 380,000 babies being born every day. Most sex happens after dinner. People in cities tend to have more sex and more different partners than people in rural communities, and people in cities tend to get married and have children later than people who live in the country. But of course there is a wide variety of behaviors.

What is a woman?

This is a question with 4 billion different answers. The discussion is more important than my answer. But to generalize, I would say that a woman is someone who can support herself, have her own life and career and friends, she can support others and be a good friend and family member. She takes time to go out with guys and see whom she likes without becoming too needy or dependent. When she wants, she can move in with a guy and become a couple, they can decide whether they want to get married, whether they want children, and they have the ability to support their children. There are many variations, and in general people aren’t getting married as much as they used to, but this is one definition girls can think about and modify as they go.

Are girls having their periods earlier?

The first period is called menarche. The age of menarche has been coming down for decades in most developed countries, but the data on this is very poor quality. This is what Wikipedia has, and it’s 30 years old:

The age of menarche is coming down; we don’t know how much.

The average age of menarche in the US is now around 11 years, with a range of 8 to 13. A recent metastudy showed that girls are developing breasts earlier and earlier. The age is coming down, and we don’t really understand why. It was coming down before smart phones, so what’s driving it?

What is sex?

The best part of this question is the discussion, not my answer. What do girls think? My answer is that sex is a million things, from thinking about sex to masturbation to phone sex to people touching to having orgasms to groups and much more. I want to make sure they understand the basic terms and don’t discuss fringe behavior. If appropriate, I ask “Can sex be bad?” What are examples of good sex and bad sex? Can sex hurt?

When you’re born, how big are your ovaries? How many eggs do you have at birth?

Your ovaries are the size of almonds. They are exactly the same size today as they were on the day you were born. You were born with about 400,000 eggs, and you still have most of them. These are some of the few cells you still carry from birth. In fact, 6 weeks before you were born, you had about 800,000 eggs, but half of them were turned into other parts before you were born (we don’t exactly know why).

This is not the same for boys. The balls are much smaller and don’t really start to make sperm until boy begins to mature.

Do kids masturbate?

Yes, kids masturbate, even if their parents don’t know about it. And, by the way, parents, your kids know about the vibrator in your nightstand drawer — trust me on that.

However much you do or don’t masturbate, it’s fine. It’s completely normal. A lot of boys 17–19 masturbate at least once a day, and I’ve met girls who do it 3–5 times every day. Nothing is wrong with any of it, unless it interferes with your other responsibilities.

How early do girls start having sex with boys?

Girls are starting sex earlier than they used to.

What is a woman’s menstrual cycle?

The chart at the top of this page is the foundation for most of this session, so I bring it as a paper handout. We’re going to look at it one hormone at a time. I want girls to relate to this, so I ask them to participate. For example, a small percentage of girls/women can feel ovulation. They have varying types, durations, and timing of periods, etc. When can you get pregnant? We go through this carefully and I answer a lot of questions. I save birth control for the next lesson.

I show a chicken egg, to show that it’s a single cell, the largest cell in the body by far. And the sperm is the smallest. A human egg is 0.1mm in diameter, a bit larger than a human hair. The sperm’s head is 5 micrometers, which is about 20 times smaller. So if an egg were the size of a bowling ball, the sperm’s head would be about the size of a raisin.

A woman’s ovaries have about 200,000 eggs each. She will have about 400 periods in her life. Here’s a short summary of the cycle:

The follicle-stimulating hormone (FSH) kicks in around the last day of menstruation and starts the next cycle. It somehow promotes some number of dormant eggs (around a dozen) as possible follicles, also called “candidates.” After a few days and a bit more stimulation, one candidate follicle emerges as a fully developed egg and the rest shrink away. We understand fairly well how this happens inside one ovary, but we still don’t understand how the other ovary knows to shut down follicle production (sometimes it doesn’t, as in the case of fraternal twins). The fully developed egg emerges from the follicle; what’s left behind develops into a lutein body, also called a corpus luteum.

Luteinizing hormone (LH) grows the lutein body until it takes up a significant amount of space in the ovary (imagine the size of a peppercorn). It causes the body to produce both estrogen and progesterone. LH peaks and releases the egg on the same day as estrogen peaks.

Estrogen does many things. It causes the egg release from the ovary and into the fallopian tube. When the woman ovulates, her cervical mucus becomes thin and clear, and her desire for sex increases.

Estrogen is a very powerful hormone. It can have a huge effect on mood. Women have about 8 times more estrogen in their bodies than men do, but it depends where they are in their cycle.

Progesterone assumes the woman has had sex and there’s a developing egg coming down the fallopian tube. As it grows by doubling from a single cell (zygote) into a clump of cells (blastocyst), it needs a place to land. So progesterone gets the lining of the uterus ready to receive the egg. It causes the cervical mucus to become more sticky and raises the woman’s body temperature slightly. At some point (I’m not sure how this happens), the uterus realizes there’s no fertilized egg and progesterone begins to crash, which starts the pre-menstrual phase of dumping the uterine lining. In the absence of elevated progesterone, the period begins.

As progesterone rises, women are often more interested in being around family and people familiar to them than being adventurous.

While it’s technically impossible to get pregnant once the egg is released from the uterine lining, girls have gotten pregnant pretty late into their cycle. The only days when it’s really safe to have unprotected sex are the red days. We’ll cover this more in another class.

In a pregnancy, progesterone continues to support the uterus in creating a placenta and establishing blood flow as the blastocyst turns into an embryo. Progesterone peaks toward the end of the first trimester. At that point, the lutein body shrinks away and the placenta takes over prducing progesterone.

Girls are interested, but even this level of detail is too much, so I don’t spend much time on the biology (even though it’s fascinating and I could go on and on). Instead, we discuss where everyone is in her cycle at that time. This leads to a discussion of how girls feel during their cycles and periods. Some women are more affected for longer than others — there’s tremendous variation. I sometimes mention how difficult periods are for sports organizers who are running big events with many women, all of whom are in different phases of their cycles. Parents often ask why womens’ periods coincide after they live together for a long time, and I explain that’s a myth, it was a bit of published research that got front-page attention but was never true.

Do all mammals menstruate?

Most don’t. Some mammals do have bleeding associated with being “in season,” but that’s not the same. The few mammals who menstruate are:

Most of the apes (chimps, bonobos, gorillas, orangutans) but not the gibbons.
Some bats
Some shrews

That’s it. You may have imagined that most mammals have periods, but you just never saw them. In fact, menstrual bleeding is extremely rare. Evolutionarily, it may be connected to hidden ovulation in humans, though that’s not the case in the other species.

If students are getting a bit restless or tired, it’s time for cookies and a drink and a stretch.

How do women get pregnant?

Again, the misconceptions are important, so I want students to discuss this before I answer. I give a general outline of the voyage of the sperm, the numbers, the pH levels, etc. Here’s a good video:

Will my Boobies get Bigger?

This is a common question. Most girls are very concerned about the size of their breasts. The moms and I are on the same page here: you get what you get, and you don’t get upset. Guys like all kinds of girls, so there’s always a market for you no matter who you are or what you look like. Normal is you. You’re normal. If you want to look different, work on it, but there’s a limited range of possibilities for each person. The range of normal is very wide. There’s no need to medicalize how anyone looks. Better to concentrate on being a great person and doing things for others than worry how many likes your Insta photos are getting.

How do men work?

How do boys develop into men? Briefly, when boys go through puberty, the balls make testosterone, and their systems are flooded with this mysterious hormone. Adult men have about 15–25 times more testosterone in their bodies than women do, which can make them dangerous, even if they normally aren’t. Once it gets going, boys can really build muscle. And it causes acne, which is why there are no miracle acne cures.

Boys generally always want sex, which women understand but find frustrating. Boys will lie about pretty much anything to get sex.

The testes are sperm factories. If you feel inside the balls, you’ll feel the beginning of the Vas Differens, which is the tube that takes sperm from the balls to the tip of the penis. It takes 72 days to produce a sperm cell. The prostate gland makes the fluid that will transport the sperm. When a man ejaculates, the walls of the vas contract and the sperm get sucked along with the fluid from the prostate gland to the tip of the penis. Only about five percent of the fluid is actually sperm cells, and there are generally between 150 million and 400 million sperm cells in each load, though those numbers can be lower or higher. Despite the hundreds of millions, only about 10,000 get through the cervix, and only hundreds make it to both fallopian tubes.

Below the prostate is a pair of small glands called Cowpers’ glands that make this clear fluid that lubricates the vas before ejaculation. Precum (pre-ejaculate) can have sperm or not. Studies have found that men either have sperm in their precum or they don’t. This makes it technically possible to make someone pregnant by withdrawing early. Mostly, girls get pregnant by guys not withdrawing early enough.

Almost all men can come, some easier than others. Most boys can get erections easily, while many men over 50 cannot. Most guys can have about one orgasm an hour if they need to, but generally after two they need at least half a day to recharge (varies considerably).

Circumcision depends on the country and the culture. I tell girls that boys who aren’t circumcised are fine, and they should understand that it wasn’t their choice. If you like someone, there are a number of unimportant factors you should ignore (but many don’t): penis length, girth, shape, and circumcision are on the list. In polls, most women prefer girth to length. But few men rank highly in the girth category.

Has anyone smelled a man’s ejaculate? What does it smell like? It smells a bit like bleach, because it’s basic. The pH of ejaculate is 8, because a woman’s vagina is very acidic (pH 5), and the ejaculate fluid has to carry the sperm through the acid. It smells a bit like bleach, and it tastes salty like ocean water.

Girls should be aware of pornographic desensitization. Hormones come in pairs. The opposing hormone of testosterone is estrogen. When men are exposed to a lot of images and videos of naked girls and sex, they get less aroused because either estrogen increases (a rebound reaction) or testosterone decreases (overstimulation), or both. These days, it’s not uncommon to find a 20-year-old boy who has a difficult time getting an erection with a girl. This is a serious issue. It can generally be “cured” by not looking at porn, but it can take a while. Resources for this at the end.

This is a sculpture by a French sculptor. It says as much about men as it does about women:

All about orgasms

You can’t cover orgasms in 15 minutes, but you can give some basics and answer questions. Only a small percentage of women never orgasm. On the other hand, maybe 20 percent come easily. But female orgasm can be complicated. Men have their own issues. In general, making yourself or another person come is a skill, and you can learn it. There is no ideal orgasm, there are just real experiences.

I go over a few things, depending on age and what they seem interested in.

There’s usually a question about toys from one of the older girls. There is usually a lot of interest in toys. I take it as Q&A, and I sometimes show some good websites to find reliable toys (see below).

They usually ask about squirting. There’s been a lot of research on squirting!! Squirting is when fluid comes out when a woman has sex. Most women either squirt normally when they orgasm, or they can learn to squirt, and men can learn techniques to make a woman squirt (especially if she’s had enough water beforehand). What comes out is essentially dilute urine (though some researchers don’t want to call it that). There’s a wide range of wetness among women, from those who are somewhat dry and benefit from using lube to those who bring a few towels to the bed beforehand.

I try to be aware of which moms and daughters aren’t up on all the concepts and terms and are just nodding their heads. The topics are different for 18-year-olds than for 14-year-olds.

Medical conditions

I cover STDs in another class. Here, I’ll just touch on four medical conditions …

Urinary tract infections are more common in women than men. This is generally a burning sensation when you have to pee or while peeing. It can make it so you can’t “hold it in” when you have to pee. They pretty much go away by themselves, but if it persists or is particularly uncomfortable, you can always go to a doctor and get antibiotics. A video visit will often do. Some women get them frequently enough that they should try to figure out how to prevent them. There are tons of websites touting herbal remedies and magical cures, but they are mostly a waste of money. See your doctor if you are concerned about anything, and be sure to drink tons of water. Ask GPT4 for a good list of ways to help prevent UTIs.

Yeast infections are common vaginal infections. They usually cause itching, sometimes burning. Usually, there is some white discharge. They are very treatable with various antifungals, some of which are available over the counter, others are by prescription. You should definitely see a doctor when you first get one, and then you and your doctor can set up a plan to avoid and get rid of them.

Endometriosis is a condition where tissues outside the uterus also have a similar period cycle, so they can become inflamed during a period. It’s usually nearby in the pelvic or core area but can also affect skin. It can be a nuisance or very painful, and there aren’t any good treatments yet. It tends to cluster in families, and fortunately it’s rare, but we still don’t know much about it.

Vaginismus is pain when the vagina is touched by someone else. This can range from a temporary thing to very painful. There are many good resources online for this condition, and even a few smartphone apps. If you have it, get help and overcome it. Most girls who have it can and do.

Other types of sex

There are many types of sex, like between women, between men, some people are bi, some are not, some are monogamous and others have open relationships. Religion often plays some role, and so do the norms of various social groups. This class has been just about girls and boys. What questions does anyone have about types of sex?

Questions and Answers

That’s plenty for one class, and we don’t have to get through all of it. No reason to rush. Can be done in several sessions. Watch for fatigue and attention drift. If parents and girls want, I can answer questions of either group without the other group in the room. I can also answer questions individually.

Summary

I’ve left a lot out, but this is a start. My goal is for parents to take the initiative, learn for themselves, and don’t rely on government bureaucrats deciding what they should learn and what they shouldn’t. Girls and parents should have a healthy ongoing dialog about sex that’s informed by research and fairness. They may not always agree, but they should strive to understand each other. Just because girls don’t understand all the dangers doesn’t mean parents should put up a force field around them and forbid everything. That’s likely to backfire later. Remember when you were a teenager. Kids are going to try things. They’re going to make mistakes. They’re going to go against your wishes. But with mutual respect and understanding boundaries, you can be more of a team and prevent anything really bad from happening.

If there’s demand, I’ll write the other chapters — just leave a comment saying what you’d like me to write about. If not, I won’t. If you haven’t subscribed to my family newsletter, you can fill out the form below.

Resources

There’s a lot of material online, and most of it is actually pretty good. You can learn new things practically anywhere. I think GPT4’s knowledge is quite good. I also think there are a bunch of myths that even doctors and professionals continue to believe. So use your critical-thinking skills and learn what’s right in the best way for you.

Books

Breaking the Hush Factor: Ten Rules for Talking with Teenagers about Sex

Let’s Talk About It: The Teen’s Guide to Sex, Relationships, and Being a Human (A Graphic Novel)

Girls & Sex: Navigating the Complicated New Landscape

Doing it!

Consent: The New Rules of Sex Education: Every Teen’s Guide to Healthy Sexual Relationships

Boys and Sex, by Peggy Orenstein

Girls and Sex, by Peggy Orenstein

The Girls' Guide to Sex Education: Over 100 Honest Answers to Urgent Questions about Puberty, Relationships, and Growing Up, by Michelle Hope

Let's Talk About It: The Teen's Guide to Sex, Relationships, and Being a Human (A Graphic Novel), by Erika Moen

S.E.X., second edition: The All-You-Need-To-Know Sexuality Guide to Get You Through Your Teens and Twenties, by Heather Corinna

Toys for girls

You get what you pay for; don’t get the cheapest thing on Amazon.

Lovense — my favorite toys by far (but expensive)
Love Honey
Bad Girls’ Bible

david siegel