Typically, fertility clinics and surrogacy agencies accept women who are between the ages of 21 and 4 because these are the healthiest years for a woman to carry a pregnancy. At 18, it is more unlikely that a woman has already given birth to a child. In any case, it depends on a case-by-case basis.
Read the full article on: How to Become a Surrogate Mother – Requirements & Qualifications ( 75).