Vanderbilt University scientists have been conducting research to find out whether cannabis use might increase the risk of ectopic pregnancies.
In normal pregnancy, eggs make their way from the ovaries to the womb through the fallopian tubes, where they may be fertilised by a sperm.
The fertilised egg continues on to the womb, where it implants itself to the wall and continues to grow.
In ectopic pregnancy, the fertilised egg takes an alternative route and can implant itself outside of the womb.
Most often it implants in the fallopian tubes themselves, but it can also latch on to the ovary, the abdomen, or the cervix.
According to Dr Sudhansu Dey and colleagues, marijuana is one of the most popular illicit drugs used by pregnant women, raising concern about its affects during pregnancy.