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When did girl can get pregnant?

The ability for a girl to get pregnant begins at puberty. Puberty is the process of physical changes through which a child’s body matures into an adult body capable of sexual reproduction. The key event is when a girl starts ovulating and releasing eggs that can be fertilized by sperm. This typically occurs between the ages of 10 and 14, but can happen earlier or later depending on the individual.

Signs of puberty in girls

There are a few signs that indicate a girl has entered puberty and is developing the ability to get pregnant:

  • Breast development – Breasts start to grow and swell. This is usually the first sign of puberty in girls.
  • Pubic and underarm hair – Hair starts to grow in the pubic area and underarms.
  • Growth spurt – Girls typically grow 3-5 inches taller as puberty begins.
  • Menstruation – Girls get their first period, meaning they release an egg that can be fertilized.
  • Acne – Hormone changes can cause increased oil production and breakouts.
  • Body odor – Sweat and oil glands become more active, leading to more body odor.
  • Wider hips – The pelvis and hips widen to prepare for childbearing.

These physical changes occur over a period of a few years. Not all changes happen at the same time, and the order they happen varies for each girl. But once a girl gets her first period, it means she has released her first egg and can potentially get pregnant if the egg is fertilized by sperm.

Average age of first period

The average age for a girl to get her first period is between 11-12 years old. However, it’s normal for it to happen anywhere between the ages of 8 and 15. Here is an overview of when most girls start menstruating:

  • By age 12 – 75-95% of girls
  • By age 13 – 98% of girls
  • By age 15 – 99.5% of girls

Girls who get their periods on the early side, before age 10, are undergoing precocious puberty. On the late side, after age 15, it is considered delayed puberty and a doctor should be consulted to rule out any medical conditions.

Can a girl get pregnant before her first period?

Yes, it is possible for a girl to become pregnant before ever getting her first period. This can happen for a few reasons:

  • Ovulation occurs before menstruation – Some girls ovulate and release an egg up to 6 months before getting their first period. If sperm is present in the reproductive tract around this time, the egg could get fertilized leading to pregnancy.
  • Irregular cycles – During the first 1-2 years after a girl starts menstruating, it’s common for cycles to be irregular. She could ovulate and not get a period that month.
  • Spotting – Sometimes girls experience random light spotting as their cycles start. They may mistake this spotting for a period, even though it occurred before they actually ovulated.

During the first two years after menstruation begins, about 50% of girls may have at least one anovulatory cycle where no egg is released. So just getting periods does not necessarily mean ovulation is occurring regularly right away.

Likelihood of pregnancy before first period

The likelihood of getting pregnant before the first period is low, but not zero. Here are the general odds:

  • At 6 months before first period: Less than 1% chance
  • At 3 months before first period: 1-2% chance
  • 1 month before first period: 5-10% chance

So in the months immediately leading up to that first period, the odds start going up progressively. But less than 10% of teenage pregnancies overall occur pre-menarche (before first menses).

Age of fertility

Fertility tends to increase in the years following menarche as cycles become more regular. Here’s an overview:

  • At menarche: approximately 20% of cycles are ovulatory
  • 1 year after menarche: 50% of cycles are ovulatory
  • 2 years after menarche: 60-80% of cycles are ovulatory
  • 3+ years after menarche: 80-100% of cycles are ovulatory

So in the first few years, the risk is lower because not every cycle releases an egg. But that risk keeps increasing as ovulatory cycles become more consistent.

By two years after menarche, fertility rates are close to that of an adult woman.

When periods become regular

Periods typically become more regular about 2-3 years after menarche. At this point girls will start having a period about every 4-5 weeks consistently. Once a regular pattern is established, it means ovulation is occurring predictably. This makes pregnancy prevention more important.

Factors affecting puberty timing

The timing of when puberty begins and menstruation starts can be influenced by several factors:


Genes passed down from both parents significantly control the timing of puberty. If a girl’s mother started puberty on the early side, there’s a greater chance she will too.

Body weight

Having a higher body mass index (BMI) is associated with earlier puberty, especially for girls. Excess fat tissue produces additional estrogen which can trigger the hormonal changes.


Chemical exposure, nutrition, and stress levels have all been looked at for potential effects on puberty timing. But most environmental impacts remain unproven.

Medical conditions

Serious medical conditions and chronic diseases can delay the onset of puberty in girls. Examples include celiac disease, cystic fibrosis, diabetes, asthma, malnutrition, and inflammatory bowel disease.


Average age for starting puberty does vary between ethnic groups. For example, African American girls tend to start at age 9, while Asian girls may start at 10 years old on average.


In summary, girls develop the ability to get pregnant when they enter puberty which brings ovulation and menstruation. This typically occurs between ages 10 and 14. Menstruation signals the ovaries have released an egg that could get fertilized. But girls can sometimes ovulate and conceive before ever getting their first period. The likelihood of pregnancy increases as girls get further past menarche and their menstrual cycles become more regular.

When to see a doctor

Consult a pediatrician if your daughter:

  • Has not started her period by age 15
  • Started puberty before age 8
  • Has periods fewer than 6 cycles per year after being regular
  • Has extreme menstrual pain or bleeding

These could indicate a medical issue requiring evaluation. Tracking the start of puberty and menstrual cycles with a calendar can help identify patterns for discussion with your doctor.

Supporting your daughter

Puberty and menstruation can be an emotionally challenging time for girls. The physical changes coincide with mental, social and behavioral changes too. Here are some tips for providing support:

  • Educate her using guides like the American Academy of Pediatrics brochure “Growing Up! For Girls”
  • Create an open, shame-free environment for discussing puberty
  • Be understanding of moodiness and withdrawl as hormone fluctuations affect emotions
  • Emphasize coping strategies like relaxation methods, sufficient sleep, healthy food
  • Ensure she knows about feminine hygiene products and proper use
  • Remind her that irregular periods are normal early on
  • Watch for signs of depression, anxiety, eating disorders and intervene if necessary

Puberty can be an exciting milestone, but also stressful. Giving your daughter support and guidance will help her navigate the transition smoothly.

Frequently Asked Questions

At what age can most girls get pregnant?

Most girls develop the ability to get pregnant between the ages of 10 and 14 when puberty begins. It starts when a girl ovulates and releases her first mature egg for potential fertilization. This typically happens about one year before getting her first menstrual period, but can occur earlier or later. By a couple years after menstruation starts, fertility is close to that of an adult woman.

Is pregnancy possible without penetration?

Yes, pregnancy can occur without penetration through a process called sperm migration. This is when sperm travels through clothing and deposits near the vaginal opening. The sperm can then move up through the cervico-uterine mucus and potentially fertilize an egg. Cases of sperm migration pregnancies are very rare, but reported in both adolescents and adults. Proper clothing and barrier methods help prevent this risk.

Can a girl get pregnant during her period?

It is highly unlikely, but still possible in rare circumstances. Menstrual bleeding occurs about two weeks after ovulation. The egg only lives for 12-24 hours. However, sperm can survive 3-5 days inside a woman’s body. So if a long menstrual cycle overlaps with late ovulation, conception could occur with sex towards the end of bleeding. But this scenario has very low odds of pregnancy.

When should girls start seeing an OB-GYN?

The American College of Obstetricians and Gynecologists recommends girls have their first gynecological visit between the ages of 13-15. This initial well-woman visit helps establish a relationship with a doctor to discuss puberty, menstrual health, sexuality, and offer pregnancy prevention counseling if necessary. Annual visits can provide important health guidance as a girl becomes sexually active.

Can girls take pregnancy tests before their first period?

Yes, pregnancy tests work by detecting the hormone hCG which is only present if implantation has occurred. So even without periods, a girl who has ovulated can take a pregnancy test 2-4 weeks after intercourse. If uncertain when to test, waiting one month after suspected conception is recommended. Home urine tests are accurate and private for early testing.

Do irregular periods decrease fertility?

Irregular or absent periods can make conception more difficult, but not necessarily. The key is whether ovulation is still occurring. With irregular cycles some months have ovulation while others don’t. Stress, weight changes, thyroid dysfunction, PCOS, and other conditions can cause irregular ovulation. Tracking basal body temperature and cervical mucus can help detect when ovulation occurs without regular periods. A doctor may prescribe medication to induce more consistent ovulation in some cases.

Is spotting before a period considered menstruation?

Spotting refers to light bleeding between periods and does not count as a menstrual period. True menstruation with a proper flow occurs after ovulation when no fertilization has occurred. Hormonal fluctuations during perimenopause or around the first year after menarche can cause irregular spotting. Spotting may also happen with ovulation, intrauterine devices, or cervical polyps. But only consistent menstruation every 21-35 days indicates a likely ovulatory cycle.

How long after menstruation can a girl get pregnant?

She can get pregnant for about 4-5 days after her period ends during the pre-ovulatory stage. Menstruation sheds the uterine lining built up from the previous cycle. Estrogen levels start rising again signalling the ovaries to mature a new egg for ovulation. Sperm can remain viable inside the female genital tract during this time and fertilize the egg once it’s released. This entire pre-ovulatory window spans days 5-13 of an average 28-day cycle.

What causes a 13 year old to start her period early?

Starting periods before age 10 (premature menarche) can have several causes:

  • Being overweight – excess fat cells produce estrogen
  • Genetics – mother or sisters who underwent early puberty
  • Cysts or tumors on ovaries – may elevate hormone levels
  • Chronic diseases – asthma, heart disease, type 1 diabetes, celiac disease
  • Radiation treatment – for childhood cancer in pelvic area
  • Congenital adrenal hyperplasia – glands produce excess androgens
  • Medications – creams with estrogen, phenothiazines

If no other cause is found, a pediatric endocrinologist can monitor growth rate and determine treatment options if the early puberty risks other mental and physical developmental issues.

Which day of menstruation cycle is best to get pregnant?

The most fertile days each cycle are the 2-3 days leading up to ovulation, when the mature egg is released. This fertile window spans between day 10 and day 17 for most women with an average 28-day cycle. Having intercourse during the days prior to ovulation gives sperm time to get into position and await the egg’s arrival. Ovulation predictor kits can pinpoint the best time to conceive.

What foods or vitamins help regulate periods?

A balanced diet rich in the following nutrients may help regulate menstrual cycles:

  • Protein – poultry, fish, eggs, beans
  • Healthy fats – avocado, olive oil, nuts
  • Vitamin B6 – potatoes, bananas, chicken
  • Vitamin E – sunflower seeds, spinach, broccoli
  • Vitamin C – oranges, strawberries, peppers
  • Iron – red meat, lentils, spinach
  • Omega-3 fatty acids – salmon, walnuts, flax seeds
  • Magnesium – almonds, cashews, oatmeal

Supplements may also help including evening primrose oil, chasteberry, and vitamin B-complex. Herbal remedies like ginger tea can help with menstrual pain and flow.