Condoms - failure rate?
If a couple have sex and he uses a condom lubricated with spermicidal cream and withdraws before ejaculation, what are the chances of her becoming pregnant? What else could cause a missed period?
The second part of your question is the nub of the matter. There is no such thing as fail-safe contraception. All methods of contraception have an associated failure rate. Given the scenario you describe the first priority for you and your partner is to exclude the possibility that your partner is pregnant. This can be done very easily since accurate and sensitive home pregnancy test kits are widely available. However, using a spermicidal cream in conjunction with a condom increases the level of contraceptive effectiveness. Therefore on the balance of probability it is unlikely that your partner is pregnant but that possibility should be excluded before other possibilities are considered to account foe her missed period.