If you are exclusively breastfeeding your baby, as long as you wake up to breastfeed, you do not need to pump at night.
If you are doing some combination of breast and bottle feeding, or if you are strictly pumping and bottling, then you will need to wake up at least once during the night to pump.
Do I have to pump at night?
It depends on if you are exclusively breastfeeding or exclusively pumping. Maybe a mixture of both.
If you are exclusively breastfeeding and baby wakes at night and you feed them, then there's no need to pump. You don't need to add extra pumps at night.
If you are exclusively pumping, it is recommended to pump during the night to help maintain your milk supply.
Talking a little bit more about milk supply and pumping at night:
Your prolactin levels, which are your breast-milk-producing hormones are highest from about midnight to 6:00 AM and if you skip pumping or breastfeeding during those nighttime hours, it may have an impact on your breast milk supply. Pumping during that time is really going to help boost your supply and keep your supply to be exactly what your baby needs.
During the early newborn weeks, it is recommended to be breastfeeding or pumping at least every three hours, 24 hours around the clock. So, sorry, you gotta wake up to feed baby or to pump.
As baby gets older and they're able to have a little bit longer stretches of sleep, you can go longer between feedings or pumping sessions at night. You still wanna keep those regular breastfeeding and pumping sessions during the day to help maintain your supply.
Anna Burch, IBCLC