If you're in a stable relationship, knowing your antibody status may be important in deciding what kind of sex you can have with your regular partner. Many people would prefer not to use condoms with a regular partner, but the only way for both of you to be confident that this is a safe option is if you both take an HIV antibody test at the same time. Then you will have to make an agreement about what sort of sex either of you will have with other partners, in order to be confident that unprotected sex will continue to be safe. You also need to agree that if either of you uses needles to inject drugs, no sharing will take place with other people.

If you are thinking of taking a test with a partner, you need to bear in mind that it is advisable to wait at least three months after the last occasion on which one of you had unprotected sex with anyone else. This is because it may take three months after infection for antibodies to HIV to appear (although the majority of people produce antibodies within two months of infection).

This is an ideal scenario. A lot of people find that they start having unprotected sex with a regular partner without having gone through this process of testing together. An Australian study found that nearly 50% of gay men had been with their partners less than three months before they first had unprotected sex.

This may happen because you assumed that either you or your partner had not been at risk of HIV infection in the past. Or it may be that you stopped using condoms without thinking through all the implications, and now want to be reassured that this was the right decision. Or it may be that you stopped using condoms after a breakage or omitted to use them on some occasions. You may have assumed that if infection was going to occur, it would have happened immediately.

In all these situations, you will need to wait for at least three months after the last occasion on which you had unprotected sex, and resume using condoms, or else take a test immediately. Depending on the result of your test and your partner's test, you will then have the following options:

• If you have both tested negative, and neither of you have had unprotected sex with anyone else for at least three months prior to this test, you can carry on having unprotected sex confident that there is no risk of HIV transmission between you. You are both clear of HIV infection.
• If you have both tested negative, but at least one of you has had unprotected sex with someone else in the past three months, a risk of transmission still exists because the person who had unprotected sex less than three months ago may not have developed antibodies yet.

If this is the case, the person who has had unprotected sex with another person will need to take another test three months after the occasion on which they had unprotected sex with another partner. If they are still negative, you can be confident at that point that you are both clear of HIV infection.

If the partner who has had unprotected sex with another person tests positive, you will need to wait at least three months after the last occasion on which you had unprotected sex together before taking another test yourself, and will need to use condoms. Remember, you may not have been infected with HIV at this point, so there is no sense in abandoning condom use.

Clearly this can be very complicated and stressful for both of you, and it is liable to arouse uncomfortable feelings in your relationship. It is at times like this that any negative feelings about sex outside your regular relationship are likely to be magnified, and resentments about previous incidents may be brought to the surface again. The support of a counsellor is likely to be especially important.

The importance of trust in this scenario

Unfortunately most advice about safer sex and HIV testing ignores the emotional context in which unprotected sex and decisions about HIV testing take place.

Most relationships are plagued by some degree of mistrust and insecurity on the part of one or both partners. Most of us would like to believe that we are capable of putting these feelings to one side, but human behaviour repeatedly shows that this is very difficult for most of us to do. In relationships where a significant imbalance in  power exists (for instance because of gender difference or age) it can be very easy for an individual to feel pressurised into unprotected sex and/or HIV testing against their better judgement. We cannot offer any words of wisdom to avoid situations of this sort because each relationship has its own problems, but one of the most important safeguards you will have in this sort of situation is to call on the counselling services available at GUM clinics in order to make the decision that is right for you. It may be particularly helpful for both of you to see a counsellor together if you are thinking of testing in order to give up condom use.

Testing in order to give up condom use requires an explicit agreement about whether or not it is permissable for either or both of you to have sex with other partners, and what sort of sex you can have with other partners.

You both need to agree what you regard as safe sex with other partners, and you need to be confident that you can stick to these agreements.

If you are thinking of having a baby

If you think you or your partner may have been at risk of HIV infection and you're intending to have a child, it makes sense to be tested. HIV can be passed from mother to baby in about 14–20% of pregnancies on average, and the transmission rate rises to around 30% if you breastfeed too. However, treatment during pregnancy with antiretroviral drugs cuts this risk very significantly. For more details see the section on HIV testing, pregnancy and children later in this chapter.

Emotional aspects of testing in relationships

If you're having the test together, how do you think this will affect your relationship? How would you feel if one of you tests positive and the other tests negative? Not only will one partner have to face up to living with HIV, but you will both have to cope with how this affects your relationship. Sometimes people cope well. They continue to practice safer sex and learn new ways to support each other.

At other times the pressure is too much and the relationship breaks up. Another possibility is that you may both test positive. This could be very difficult to deal with, especially if you both fear that one partner infected the other.