Towards Optimal Fertility, Fathering and Fatherhood studY

Inclusion Criteria: Subfertile couples: * men aged ≥21-49 years * men with a female partner aged 21-39 years * couples who are not able to conceive for at least 12 months * couples who are Singapore citizen or permanent resident Fertile couples: * men aged 21-49 years * men with a female partner aged 21-39 years * men with proven fertility defined as those female partners who are currently pregnant and with viable intrauterine pregnancy at gestational weeks of less or equal to 16 at the time of the study * couples with attempted time to conceive within 12 months to achieve this pregnancy or with unplanned pregnancy * couples who are Singapore citizen or permanent resident Exclusion Criteria: Subfertile couples: * male infertility of a known aetiology including azoospermia, retrograde ejaculation, genetic disorders, cancer treatment, or testes trauma * female infertility diagnosis as confirmed by diagnostic imaging or having severe endometriosis * female partners with irregular menstrual cycle \>35 days * couples with known chromosomal abnormalities Fertile couples: * couples who achieve pregnancy after oocyte or spermatozoa donation * couples with known chromosomal abnormalities * female partners with known uterine abnormalities