Labour has called for a ban on parents-to-be from using blood tests to determine the gender of their baby in the early stages of pregnancy.
The call comes amid concerns that some could choose to terminate the pregnancy because of a foetus's sex.
The non-invasive pre-natal test (NIPT) is used to detect Down's syndrome and other genetic conditions and is being rolled out by the NHS as an additional part of its antenatal screening offer.
Parents-to-be who take the test on the health service cannot use it to learn their baby's gender, however they can pay for it privately, including via online services.
Labour MP Naz Shah, shadow minister for women and equalities, said a preference for boys in some cultures could force expecting mothers and fathers "to adopt methods such as NIPT to live up to expectations of family members".
"NIPT screenings should be used for their intended purpose, to screen for serious conditions such as Down's syndrome," she told the BBC's Victoria Derbyshire programme.
"The Government needs to look into this exploitative practice and enforce appropriate restrictions."
On the NHS, parents-to-be are offered a combined blood and ultrasound test in the first three months of pregnancy to check for abnormalities.
Most women and couples can find out the sex of the foetus at the 18 to 20-week scan offered by the NHS.
Using NIPT, the gender of the fetus can be determined from nine to 10 weeks of pregnancy.
A 2017 report by the Nuffield Council on Bioethics found several websites offering 'baby gender tests' for around £170.
The council said that unless finding out a baby's gender is used to diagnose a gender-related medical condition, there is no clinical need for it at an early stage.
The report warned that, while there was limited evidence gender-selective terminations were taking place in the UK, there was a "real possibility that permitting NIPT for sex determination in the UK may be encouraging sex selection".
It is illegal to abort a pregnancy because of a foetus's sex alone, although there are some exemptions and the council said that laws are not "clear-cut".