There's no doubt a strong connection between a mother and her child exists, but there's more to that. They even share the same heartbeat rhythm.
A few years ago, scientists discovered that babies and their mothers can synchronize their heartbeats just by looking at each other. The researchers explained their discovery in the following words,
Mothers and their 3-month old infants were observed during face-to-face interactions while cardiac output was collected from mother and child. Micro-analysis of the partners' behavior marked episodes of gaze, affect, and vocal synchrony. Time-series analysis showed that mother and infant coordinate heart rhythms within lags of less than 1 s.
Apart from that, a Japanese scientist discovered that playing the tape recording of a mother's heartbeat helps to put crying babies to sleep. The same occurs when a crying baby is held on the left side by the mother, enabling the baby to hear the heartbeat. This is exactly why fathers have a hard time soothing their babies while the mothers don't. So, don't worry fathers, your baby does love you, but your wife has magical powers (Not so magical now though)
According to many psychologists, this experience is imprinted on the infant's mind, because of which, the repetitive sound never loses its ability to lower the stress levels for the rest of one's life. So, if you're stressed out, go and hug your mother.