奉子成婚即先孕后婚，又称先有后婚，亦有“先上车后补票”之谑称，指的是男女双方因婚前性行为而使女方怀孕，之后因为责任、面子或让子女能在完整家庭成长等问题而成立的婚姻。多数案例是因为不安全性行为所致。有些同居男女则是有计划地在女方怀孕后才正式结婚，有些甚至在子女出生后才结婚。

奉子成婚是因奉旨（皇帝的圣旨）或媒妁之言，从前的婚姻多由父母决定，由于「子」和「旨」音相近（广东话等更是同音），故人们说笑地把「旨」改做「子」，演变成现今的“奉子成婚”这个词语。另一个同类的词语——“先有后婚”来自「先友后婚」（先做朋友后结婚），因为日常口语里「有了」指怀孕，而「友」、「有」同音，故「友」被改成「有」，用以表示先怀孕后结婚的意思。

A shotgun wedding is a wedding that is arranged to avoid embarrassment due to premarital sex possibly leading to an unplanned pregnancy, rather than out of the desire of the participants. The phrase is an American colloquialism, though it is also used in other parts of the world, based on a supposed scenario (usually hyperbole) that the father of the daughter that had premarital sex, almost by accepted custom, must resort to using coercion (such as threatening with a shotgun) to ensure that the man who possibly impregnated her follows through with the wedding.