Here's Why Your Breasts Have More Milk In The Morning, According To Science

by Sarah Bunton

Like many aspects of motherhood, breastfeeding is seemingly just another thing you have to do without the help of a manual. Even if you are lucky enough to have mastered your lactation routine, you probably still have a few breast milk questions lingering in the back of your mind. For instance, have you ever questioned if your breast milk output is higher in the morning, or if you're just imagining things? Well, you're definitely not alone.

I'll be the first to admit that — despite highlighting and dog-earing multiple pages in my various parenting how-to books — I really had a limited understanding of why and how breastfeeding works the way it does.

Actually, there are scientific reasons for why you've gone to sleep and woken up to damp sheets and leak pads that didn't quite live up to their end of the bargain. Experts in the fields of medicine and lactation offer several explanations as to why your milk supply output is so much higher in the morning than it is at any other part of the day. So check out some of the surprising and interesting factors that cause your output of breast milk to be higher in the morning, according to science.


Storage Capacity

Every body is different and how much milk your breasts are able to hold varies greatly, too. To put it simply, "storage capacity is the amount of milk that the breast can store between feedings," as International Board Certified Lactation Consultant Kelly Bonyata noted on KellyMom. In terms of why some women might experience differing levels of milk productions, it could depend on the breast milk capacity. "A mother with a smaller storage capacity will need to nurse baby more often to satisfy baby’s appetite and maintain milk supply since her breasts will become full (slowing production) more quickly," Bonyata further explained. So it's totally normal if your output is higher in the morning since your breasts tend to get fuller, faster.


Peak Hormone Hours

If pregnancy was any indication then you probably already know how your hormones can fluctuate and affect your body. There's one hormone in particular, though, that plays a major role in milk production. "Prolactin is necessary for the secretion of milk and stimulates the growth and development of the mammary tissue, in preparation for the production of milk," according to Infant and Young Child Feeding: Model Chapter for Textbooks for Medical Students and Allied Health Professionals from the World Health Organization (WHO). As it turns out, most of the breastfeeding hormone prolactin is produced at night, as the aforementioned WHO textbook further explained. So it makes sense that the higher prolactin levels which increase your milk production would result in you having a higher output when you wake up in the morning.


Fat Content

Does a higher output of breast milk have to do with a higher fat content of your breast milk? According to the official site for Lactation Consultants of Central Florida (LCCF), "while milk production is at its highest in the morning, breast milk is higher in lactose and lower in fat and protein during this time." As it turns out, the fat content that increases in the evening, has a lot to do with why your breasts are so full in the morning.

"The higher fat content of breast milk [produced] in the evening hours is designed to help babies sleep longer stretches at night," the site for LCCF further noted. So, by being able to get a large chunk of uninterrupted sleep, your breasts have plenty of time to refill, leading to the higher output after you wake up in the morning.

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