Forceful letdown/over active letdown and Over supply

An over active letdown is often confused with an over supply of milk. Though they often happen together, this is not always the case. With an over active letdown, you have an abundance of milk only during the beginning of the breastfeeding session. With an over supply of milk, you always have extra milk and your baby will show over supply signs constantly. An over active letdown and over supply can happen anytime, but most commonly begins to occur around three to six weeks. To solve a forceful letdown and/or an over supply problem you need to take steps to control your milk flow, and help your baby learn to control your milk flow. Sometimes it takes a few weeks of interventions before your supply regulates.

Signs that you have an over active letdown:
Baby gags, coughs, chokes, gasps or gulps while breastfeeding, especially during letdowns.
Baby acts like the milk is coming out too fast.
Baby pulls unlatches when you letdown.
Baby clamps down or bites your nipple to control the flow.
Baby spits up often, and is very gassy.
Baby sometimes refuses to breastfeed.
Milk sprays when baby unlatches. (Especially during letdowns)

Signs that you have an over supply:
Baby gas, chokes, gasps, or gulps while breastfeeding.
Baby acts like the milk is coming out too fast.
Baby unlatches many times during the breastfeeding session.
Baby clamps down on your nipple or bites during the breastfeeding session.
Baby spits up often, is very gassy, and has very green stools.
Cries like he or she is hungry, but then does not want to breastfeed.
Milk sprays when baby unlatches.
Baby may only want to breastfeeding for 5-10 minutes at a time.
Mother may have reoccurring mastitis and plugged milk ducts.

Solutions for over active letdown and over supply:
Your baby’s position while breastfeeding can affect how fast she or he is getting milk. Leaning back while you breastfeed (in a recliner or with pillows behind your back) allows you to utilize gravity to slow your milk flow. This can be done with any breastfeeding position, or you can place baby tummy to tummy with you.
Have baby sit on your lap facing you, with his or her legs straddling one of your legs.  
Side lying position allows the baby to dribble any excess milk out of her mouth while breastfeeding. Breastfeeding frequently will reduce the amount of milk that is in your breasts at each feeding, but will also tell your breasts to continue making a lot more milk. Block feeding can be very helpful. Block feeding is when you breastfeeding on only one breast for a period of time before switching to the other breast. Most moms are successful with a block of switching breasts every two feedings (or every two-three hours), but you can try three or four feedings (5-6 hours) on each side if necessary.
If you have an over active letdown, allow baby to latch and as letdown occurs, unlatch baby and catch the flowing milk in a cloth, then relatch the baby.
Hand or pump express a little bit of milk before breastfeeding your baby. Be careful not to express too much, or you will signal your body to continue making milk. Only express enough to get a letdown, and then breastfeeding your baby.

Around 12 weeks postpartum your body goes through some more hormone changes to make your milk supply more stable. Many moms find that their over active letdown and over supply problems begin to go away at this point.