Image: Sarah Brison/JustGiving.

In July this year, Sarah Brison suffered a heart attack that left her in a critical condition.

The UK nursery nurse and semi-professional soccer player, who was 23 at the time, awoke one morning in “unbearable” pain and the sensation that her body was shutting down.

“Everything went blurry. Then, within seconds, I lost my vision completely. I couldn’t feel my limbs, had no control over my body and I was sweating uncontrollably,” Brison, now 24, tells The Sun.

“It was like brain freeze except it was all over my chest, as if someone was pressing down on me with all of their weight.”

Although the symptoms clearly worried her, Brison assumed she was having a panic attack that didn’t require medical attention. She even apologised to the paramedics who arrived on the scene after her boyfriend Billy called for an ambulance. She thought she was wasting their time.

However, it’s likely that phone call saved her life. Brison had in fact suffered a heart attack; her blood pressure was dangerously low and her heartbeat was abnormal.

"They say your hearing is the last sense to go before you die. Everything else had gone." (Image: JustGiving)

Hospital tests soon revealed she had clots on the vessels leading to her heart. It turned out Brison also had a hole between the two top chambers of her heart, through which a clot had managed to pass.

"I just kept asking the doctor how it could have happened ... Surely 23-year-olds didn't have heart attacks? I kept asking if I was going to die," she tells The Sun.

One consultant offered a possible cause: the contraceptive Pill. Brison had been using the contraceptive for seven years but had recently switched from a mini pill to the combined pill.

“I had heard about it being linked with an increased risk of blood clots so I asked my doctor if it was safe. But my GP told me it would be highly unlikely anything would happen," she recalls.

Like Brison, you've probably heard of the link between the Pill and blood clots — and read stories about women who have suffered fatal health complications as a result. However, it's very important to remember this risk is small. (Post continues after video.)

“Combined pills do increase the risk of blood clots in all women who use them, but that absolute risk is very, very small,” says Dr Deborah Bateson, Medical Director of Family Planning NSW.

Evidence suggests this risk is increased around two to three times in combined pill users compared to non users, with a baseline rate of ten women per 10,000 affected per year.

“For most women of reproductive age who are taking the Pill that risk is extremely low; in fact, much lower than the risk of blood clotting in pregnancy or immediately after delivery. There’s a risk of a spontaneous blood clot in all non-Pill users as well," Dr Bateson explains.

The risk of blood clotting among users of the combined pill is effected by the level of oestrogen in its formula. Since the Pill was introduced in Australia, this dose has been gradually reduced from its original higher levels.

Dr Bateson says the low-dose Pills available today are a very safe formulation, and despite reports to the contrary, research is yet to determine whether certain brands are associated with a higher clotting risk.

"That absolute risk [of blood clots from the Pill] is very, very small." (Image: iStock)

Although the risk of blood clots is low for most women who use oestrogen-based birth control, there are factors that can make them unsafe for some women. These factors include past experience with a blood clot, a strong family history of clots, or a mutation that increases susceptibility to developing one.

For this reason, it’s important for GPs to take a good family history before prescribing birth control; it’s rare that an existing risk factor won’t show up in a woman’s family previously.

Dr Bateson says there are a few other blood clot risk factors that make some people ineligible to use the combined pill or other oestrogen-based birth control methods.

A woman who is immobilised or very overweight would be ineligible, while smoking and age are also viewed as risk factors — doctors generally stop prescribing the Pill for women when they reach the age of 50. (Post continues after gallery.)

Popular forms of birth control

Intrauterine device

IUDs are small, T-shaped devices that are inserted into the uterus by a doctor in order to prevent pregnancy. There are two types of IUD: copper, which affects the movement and survival of sperm in the womb while changing the lining of the womb;and hormonal, which releases progestogen (a synthetic version of the naturally-occurring hormone progesterone) into the uterus. Although IUDs have a success rate of more than 99%, only around 2% of Australian women currently use one.

Contraceptive pill

The Pillis the most popular form of birth control. There are two types: the combined pill, containing two hormones, and theprogestogen-only, or mini, pill, which only contains one female hormone. The combined pill works by preventing the ovary from releasing an egg each month. The mini pill changes the mucus at the entrance of the uterus, which stops sperm from entering. Both are 99.7% effective; however, they don't offer protection from STDs.

Condoms

The male condom is a barrier contraception that prevents both pregnancy and the transmission of STDs. They work by collecting semen so it doesn't enter theman's partner's body. Condoms are 95 to 99% effective at preventing pregnancy.

The female condom

The female condom is a pre-lubricated sheath, which loosely fits inside of the vagina. The condom has a removable ring, which helps to insert the sheath and keep the condom in place. A larger ring remains on the outside to cover the opening of the vagina. They are designed to fit all women and can only to be used once. Due to misuse of the product it is only 79 per cent effective.

Diaphragm

Like the male condom, the diaphragm is a barrier method of contraception. It's a shallow silicone dome that's inserted into the vagina andcovers the cervix, which is the entrance to the uterus. It's held in place by the pelvic muscles, and works by preventing sperm from entering the uterus. After sex, diaphragms need to remain in placefor another six hours, in which time the sperm inside the vagina die. This method is 88 to 94% effective at preventing pregnancy, although this rate increases with experience.

Birth control implant

This is a 4cm-longimplant that is inserted into a woman's upper arm, just under the skin, by a doctor. It releases a hormone called etonogestrel, which prevents ovulation and thickens the mucus in the cervix, which can stop sperm from entering. Contraceptive implants - usually sold as Implanon - are removed under anaesthetic every three years, and are close to 100% effective.

Vaginal ring

Vaginal rings are soft plastic rings that contain the same two hormones as the combined pill - oestrogen and progestogen. The ring is inserted into the vagina, where the hormones are absorbed into the body and then prevent the ovaries from releasing eggs. Once inside the ring can't be felt, and it needs replacing every three weeks (with one week's break in between). When used correctly, this method is more than 99% effective.

Depo Provera

Depo is a long lasting hormonal injection. The synthetic form of progesterone is administered every 12 to 14 weeks to woman, preventing pregnancy within this ongoing time period. The injection, which is given in the buttock or muscle of the upper arm, prevents ovulation and thickens the mucus in the cervix, helping to block sperm. The injections are 99 per cent effective but do not protect against STDs. Male contraceptive injections are currently being trialled

The morning after pill

Emergency contraception (popularly referred to as the morning after pill) is used to prevent a pregnancy following unprotected sex. Other reasons include missing a contraceptive pill or a condom breaking. It is common in Australia to use the progestogen-only method. This entails a dosage of EC pills containing progestogen or the synthetic version. A doctor can prescribe the pill or they can be bought over the counter at a pharmacy without a prescription. Emergency contraceptionis 85 per cent effective in reducing the risk of pregnancy.

Sterilisation

Sterilisation is a permanent form of contraception. For women there are two types of sterilisation: tubal ligation, in which clips are placed on the fallopian tubes, or tubal occlusion in which a device is inserted into the tubes. These methods work by preventing the sperm from reaching the egg. Tubal litigation is 99.5 per cent effective. The Vasectomy (for men) works by cutting and blocking the tubes called the vas deferens, preventing sperm from leaving the testicles. The chances of impregnation with a vasectomy are 1 in 1000.

The good news is, there are several alternatives available for the small number of women who can’t use oestrogen contraceptives. There are progesteron-only methods, like the hormonal intrauterine device (IUD) and hormonal implant, or methods that contain no hormones at all, like the copper IUD.

If you’re concerned about the risk of blood clots, make an appointment to talk through your birth control options with a GP, or give the Family Planning Talkline (1300 658 886) a call, before taking any action independently.

“For those women who are choosing the Pill, it’s a very, very safe option indeed that’s been used for a long time. We’re certainly happy to prescribe the Pill for women when we’ve taken a good family history and we know they haven’t got those additional risk factors for blood clots," Dr Bateson says.

As for Sarah Brison, she is still having regular checkups and takes five types of medication a day, including blood thinners. She's been advised to stop taking the Pill. “Getting some normality back after the past few months has been surreal. Having a heart attack has changed my outlook on life. It’s made me see what’s important," she tells The Sun.

Do you use the Pill? Have you ever been advised not to for health reasons?