For new moms, breastfeeding can be frustrating— and rewarding. Here are some surprising facts that will help you understand what your body is going through.

1. Breast milk isn’t always white.
Breast milk is usually white or cream-colored, but it can also be green, blue, yellow, or orange. You might also notice that it’s thicker one day and more watery the next. Either way, it’s perfectly normal and nothing to be worried about, said Sara Chana Silverstein, an international board-certified lactation consultant, master herbalist and creator of the Savvy Breastfeeding app.

2. One breast will produce more.
Just like one of your hands is bigger, your breasts are probably different sizes too. So one may outperform the other, but it doesn’t mean you won’t have enough milk for your baby. Nevertheless, always start feeding on the side that you finished with last time to try to equal the two out.

“We want the same type of stimulation to help with production,” said Cindy Shelton, a registered nurse and an international board-certified lactation consultant at Los Robles Hospital in Thousand Oaks, Calif.

3. You may feel outrageously large.
It’s not a look you’re going for as a new mom, but get ready for your breasts to be engorged and larger than they have ever been, especially in the beginning.

“Milk increases in volume that third to fifth day and it does it with a vengeance,” Shelton said.

How large your breasts get really depend on your skin’s elasticity. And as your baby gets older and you’re feeding less frequently, they won’t be as engorged. When you stop breastfeeding, your breasts may end up smaller or bigger than before you were pregnant.

4. Breast milk doesn’t only come out of your nipple.
Since there are approximately 15 to 25 milk ducts in each breast that make milk, there are several pores in each breast where milk comes out of, not just the single hole in your nipple.

5. You’ll leak— especially when you least expect it.
Stock up on breast pads, ladies! Especially in the beginning, when your baby (or even another baby) cries, your breasts will let down on both sides. It may also happen when you look at your baby, at his photo, or when it’s time for a feeding.

6. Sex might be painful.
Lack of estrogen can cause vaginal dryness and make intercourse painful. Use a water-based lubricant or talk to your OB/GYN about ways to cope.

7. You could have too much milk.
Some women have a strong milk ejection reflex that causes breast milk to come out quickly and spray everywhere. Some babies even choke because they can’t keep up with the flow. Talk to your lactation consultant about techniques that can help slow down the flow.

8. You might go on an emotional roller coaster.
Oxytocin, the hormone that contracts the muscles in your milk ducts to let down milk will make you feel calm and relaxed, even sleepy. Yet some women with a strong milk ejection reflex may also experience nausea, weakness, sweating and anxiety because of the intense hormonal shift, Silverstein said. Some women may also experience intense thirst and may need to add minerals to their water. Speak to your lactation consultant about ways to cope.

9. You don’t need extra calcium.
Drinking milk won’t help you make milk, yet breastfeeding may cause your bones to shrink. The good news is that once you stop breastfeeding, experts say bone density returns. What’s more, studies show that breastfeeding can prevent osteoporosis. The National Academy of Sciences recommends breastfeeding moms get 1,000 milligrams of calcium each day from dairy, vegetables, nuts and seeds. Weight-bearing exercises can prevent osteoporosis as well.

10. An orgasm can make your breasts leak.
Since oxytocin, the hormone responsible for milk letdown is the same released when you orgasm, you could spring a leak at the most inopportune time. A bra with breast pads and a sense of humor can go a long way.

“There’s no need to be embarrassed—many women experience it,” Shelton said.

11. You can eat more and still lose weight.
Your body needs between 300 and 500 extra calories a day for breastfeeding. Yet instead of worrying that you’re eating enough, just listen to your body and the pounds should melt off in no time.
“Feed your hunger and you’ll find that you’re eating those extra calories,” Shelton said.

12. Your period may stop.
If you’re exclusively breastfeeding— no bottles (even with pumped milk) or pacifiers— and you’re feeding on demand, chances are you won’t have your period, Shelton said. Some women will get their periods back six weeks after delivery, when they start to wean, or not until they’ve stopped breastfeeding altogether. Even if you don’t have your period, it doesn’t mean you’re not ovulating so be sure to use birth control if you’re not planning to have another baby any time soon.

Julie Revelant is a health journalist and a consultant who provides content marketing and copywriting services for the healthcare industry. She's also a mom of two. Learn more about Julie at revelantwriting.com.