The easiest way to get pregnant while on Birth Control would be to use the birth control product incorrectly. Most birth control methods are only effective if used right and simple mistakes can result in unexpected pregnancies. Even when used right no birth control method is perfect and you can still fall pregnant in rare cases.
From the phrasing of your question though it sounds like you want to get pregnant without the father's consent. That's clearly a bad thing to do and if you think it will make him stay with you and love you more then you'd probably be suprised to find out the opposite is more common and while he might not "run a mile", the relationship will probably not work out.
not very common.
Birthe Hegstad was born in 1966.
Birthe Kjær was born in 1948.
Birthe Hansen was born in 1944.
Birthe Wilke was born on March 19, 1936.
Birthe Wilke was born on March 19, 1936.
Birthe Kirk was born on October 22, 1942.
Birthe Wingren was born in 1967, in Basel, Switzerland.
Birthe Qualmann was born on July 1, 1945.
Birthe Neumann was born on April 30, 1947, in Denmark.
Birthe Rønn Hornbech was born on October 18, 1943.
Birthe Rønn Hornbech was born on October 18, 1943.