The goal of this clinical trial is to test whether sexual intercourse the night after embryo transfer affects thawed embryo implantation rates. Women undergoing one of their first four frozen embryo transfers with a good quality embryo will be randomly assigned to two groups. The study group is subjected to have intercourse without using a condom at the evening/night after the embryo transfer, while the control group will abstain from intercourse for the next 48 hours after the transfer. Researchers will compare the ongoing pregnancy rates between the intervention group and the control group.

It is currently unclear whether sexual intercourse the night after embryo transfer, with or without semen ejaculation, is detrimental to thawed embryo implantation rates.

The following study is a prospective, randomized, clinical trial, including patients attending our university-affiliated Infertility and IVF center.

The goal of this clinical trial is to test whether coitus the night after embryo transfer affects thawed embryo implantation rates. At the day of the embryo transfer women (ages 18-41yrs) undergoing one of their first four frozen embryo transfers with a good quality embryo will be randomly assigned to two groups. The study group is subjected to have intercourse without using a condom at the evening/night after the embryo transfer, while the control group is subjected to abstain for the next 48 hours after the transfer.

The day after the embryo transfer an electronic questionnaire will be sent to the patients to confirm whether they had intercourse or not. The questionnaire will also address whether male ejaculation was performed intravaginally and whether female orgasm occurred.

12-14 days after the embryo transfer a BHCG serum test will be performed. For those patients with a negative BHCG test surveillance will be stopped. For those with a positive BCHG test a gynecologic US will be performed at week 6. After wards surveillance will cease for all participants. Researchers will compare the ongoing pregnancy rates between the intervention group and the control group.

Inclusion Criteria:

1. Women age 18-41yrs.
2. BMI (body mass index) of 18-35 kg/m².
3. Patients undergoing one of their first four frozen embryo transfers.
4. Patients transferring a good quality embryo, either a cleavage stage embryo or a day 5 blastocyst.

Exclusion Criteria:

1. Patients age above 42.
2. Moderate or poor-quality embryos.
3. Patients with hydrosalpinx or uterus malformations.
4. Patients who are not able or are not interested in having vaginal intercourse (same sex couples for example).
5. Couples undergoing preimplantation genetic diagnosis when natural cycle frozen embryo transfer is planned (as they are instructed to avoid intercourse).