If you’re over 40 or can no longer produce healthy eggs, donor eggs can help you carry and deliver a baby. This is also a good option if you’re at risk for passing a genetic disease such as Tay-Sachs disease or sickle cell anaemia to your child.

Treatment: What to expect

If you decide on an anonymous egg donor, you can find her through your fertility clinic. You’ll usually be able to choose based on her physical characteristics, ethnic background, educational record, and occupation. Most donors are between 21 and 29 years old and have undergone psychological, medical, and genetic screening. Ask how your clinic screens candidates — some do less extensive tests and background checks than others. If you choose to use donor embryos, you can either pick an unrelated egg and sperm donors or use a frozen embryo donated by a couple that had extras.

Once you pick a donor, both you and she will take birth control pills to get your reproductive cycles in sync — she needs to ovulate when your uterine lining can support an embryo. She’ll also take a fertility drug to help her develop several mature eggs for fertilization, while you will receive estrogen and progesterone to prepare your uterus for pregnancy. Once her eggs are mature, your doctor will give her an anaesthetic and remove her eggs from her ovaries by inserting a needle through her vaginal wall using an ultrasound for guidance.

From here on out, the procedure is just like that of in vitro fertilization (IVF). Your partner’s sperm or a donor’s sperm will be combined with your donor’s eggs in a dish in a laboratory. Two to five days later, each of the fertilized eggs will be a ball of cells called an embryo. Your doctor will insert two to four embryos into your uterus through your cervix using a thin catheter. Although it’s not a common practice, many experts say couples should consider the transfer of a single embryo to avoid the risk of twins or triplets. Extra embryos, if there are any, may be frozen in case this cycle doesn’t succeed. If the treatment does succeed, an embryo will implant in your uterine wall and continue to grow into a baby. In about 40 percent of ART pregnancies using donor eggs, more than one embryo implants itself and women give birth to multiples.