The image of a kindly stork carrying an infant to expecting parents became very popular in the Victorian era.  It was at this time that many people developed a prudish attitude towards childbirth and also the facts of life. Rather than explaining the details to children, parents would just inform them that a stork had brought their new brother or sister.  It was also during these years that pictures of baby-laden storks pursuing young, single women down the street were often used for comic postcards.

Today, most people accept that storks are not actually responsible for the appearance of babies, or for fertility rates. However, the association between storks and babies continues; so does the evasive response to curious children,
“Look what the stork has brought for you".