Healthy living

Relationships, sex and other stuff – getting pregnant

When a penis enters a vagina during intercourse, it is possible for the girl to get pregnant.

This is the case even if:

  • she has not had her first period
  • the boy withdraws his penis from her vagina before ejaculating
  • the girl is having her period
  • it is the first time she has had sexual intercourse.

Missed periods

The first sign a girl may be pregnant is when her period doesn’t come when she expects it to. If this happens, it is very important to see a doctor or talk to an adult as soon as possible.

Contraception (birth control)

The safest and surest way to prevent a pregnancy during sexual intercourse is to use contraception. If you decide to have sex, it is very important to talk together about what you might choose for contraception and then to use it when you have sex. The responsibility for contraception ought to be shared equally.

Options for boys include condoms, which help prevent sexually transmitted infections during sex. Options for girls include the contraceptive pill, which must be taken each day and is available by prescription from a doctor. No contraceptive method can be 100 per cent guaranteed. It is therefore important to be informed about the range of contraception available and to weigh up the risks attached to each one.

The human body is sophisticated, and geared towards reproduction. For contraception to be effective, it must be used in the way it is intended.

Conception (falling pregnant)

Around 14 days before a girl’s period is due, her ovaries release an egg. This part of the menstrual cycle is called ovulation. Ovulation is the ideal time for a pregnancy to occur if a man and woman have unprotected penis-to-vagina intercourse.

During sex, when a man ejaculates (comes, reaches climax, orgasms) inside a woman’s vagina, the equivalent of about 1 teaspoon of semen – containing millions of sperm – is released into the vagina. The sperm swim into the uterus and fallopian tubes. If just one sperm implants itself into the released egg, fertilisation occurs. If the fertilised egg implants in the wall of the uterus, conception occurs and a new human life begins.

The above conditions are ideal for conception. But it is quite possible for a woman to fall pregnant even if:

  • sex occurs at another time in the menstrual cycle
  • the man has not ejaculated (this is because sperm is also present in the pre-cum, the clear fluid released from the penis prior to ejaculation)
  • any semen, including pre-cum, is deposited in or just outside the vagina
  • she has not had an orgasm during intercourse.

Being pregnant

How does someone know if they are pregnant?

An egg that has been successfully fertilised by a sperm remains in the lining of the uterus. Rather than being shed, this lining stays to nourish the egg. Therefore, the woman does not have her usual period.

A missed period can be the first sign of pregnancy. Because pregnancy dates from the time of the last period, a woman might be 4, 5, 6 or more weeks pregnant before she realises it. She may not experience other physical symptoms (such as fatigue, nausea and breast tenderness) until a little later.

Decisions about pregnancy

Deciding to get pregnant is perhaps the most important decision a couple can make.

An unexpected, unplanned pregnancy places enormous pressure and anxiety on the couple involved. If someone discovers they are unexpectedly pregnant, it is important to seek help as quickly as possible. They will need to talk to people close to them and/or health professionals who can advise them of the full range of options, considerations and choices.

What happens during pregnancy?

It takes 40 weeks (approximately 280 days, or 9 months) for a baby to be ready to leave its mother’s womb. During this time it remains in its mother’s uterus, protected by a watery sac and nourished by a placenta.

The placenta, attached to the inner wall of the uterus, develops with and nourishes the baby. The placenta is also attached to the fetus, by the umbilical cord. All the oxygen and nourishment the fetus needs comes through this cord. The umbilical cord also carries waste products away from the fetus. Waste products are returned to the woman’s circulatory system and are passed out through her lungs and kidneys as part of her normal body functions.

During the first 8 weeks the baby is called an embryo. After that, it is called a fetus.

During the pregnancy, the woman’s circulatory system is separate from the blood system of the fetus. But even so, everything she does during this time can have a direct impact on the wellbeing of the baby. During pregnancy, it is very important for the mother to:

  • eat healthy food
  • not misuse alcohol or drugs.


The baby is born about 40 weeks after the last period. The average newborn baby is about 45 to 50 cm long and weighs between 3 and 4 kg.

Once the baby has been born, the doctor or midwife ties or clamps the umbilical cord and cuts it about 5 cm from the baby’s tummy. The short piece left attached to the baby dries up and usually drops off within a few days. The place where it was attached heals and becomes the navel (umbilicus, or belly button).

After the birth

A newborn baby is utterly helpless and dependent on those responsible for it, all day, every day. It needs parents and carers who will love it and put its needs before their own for many years.

  • If you have any sort of problem you want to talk about confidentially with a trained counsellor, call Kids Help Line (24 hours) on 1800 551 800 (free from a land line only).
  • Visit The Hormone Factory (external site), a great site with lots of answers for 10 to 12 year olds, especially about puberty.
  • Other good sites for teenagers include Get the facts (external site) and I stay safe (external site).
  • Read the section for young people on Avert (external site). This section is a good for sexuality education.
  • For general health information call healthdirect Australia on 1800 022 222.
  • For information about sexual health and contraception:
  • For help with sexual abuse or assault, phone the Sexual Assault Resource Centre (24 hour emergency line) on 9340 1828 for metro callers or 1800 199 888 for country callers (free from land line only).
  • Young people who are questioning their sexuality can call the Freedom Centre on 9228 0354.

Last reviewed: 07-12-2018

Public Health

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.

Text: Let's talk about sex. Information about safe sex, STI, relationships and more.