Whether it's the woman who says she was kicked out of Planet Fitness for showing off her baby bump or the six-and-a-half month pregnant woman who shocked people when she completed the Boston Marathon, or even the pregnant weight lifter that caused people to gasp, it seems that pregnant women exercising are causing some controversy these days.

In fact, according to the American College of Obstetricians and Gynecologists, working out while pregnant (if signed off on by your physician) is very important for yourself and your baby. Regular exercise can help reduce many maternal aches and pains, increase energy during pregnancy, and may speed up the labor, delivery, and recovery process.

"I think about pregnant workouts as training for a marathon—but you're training for labor," says Lisa Druxman, M.A., creator of Fit4Mom and its Fit4Baby class, an interval-based exercise routine for pregnant women that combines strength training, cardio, stretching, and balance. "You want to make sure you're as fit as possible, especially if you're thinking of having natural childbirth. Let the core work and squats start now!"

Here, Lisa—author of Lean Mommy—shares her tips for working out the right amount and doing it in a way that's safe for you and your little munchkin.

It's never too late to start working out

"You can begin exercising at any trimester, you just have to take it slowly. For the woman who wasn't working out pre-pregnancy: Start walking and every day walk a little longer. I believe what is measured, gets done. Keep a journal of your workouts and each day add another few minutes of exercise, add another rep. The best workouts to begin with are walking, swimming, and strength training with squats and lunges and core exercises."

Always fuel up before a workout

"I recommend a snack 30 minutes before working out because it gives you energy and helps you burn more fat. You want to snack on things that are high in nutrients—no empty-calorie foods. Nuts, protein shakes, fresh fruits, and vegetables are your best options. "

Exercise to feel good, not to feel pain

"Your baby feels everything you feel. So if when you're exercising, you're feeling good and energized, your baby will too. But you never want to push yourself to the point of exhaustion. Doctors used to say don't go over 140 heart beats per minute, but that is so out of date. We now go by a talk test. If you're able to talk easily while exercising, you're probably not working hard enough. But if you are so out-of-breath, exhausted you're probably working out too hard. We want you to be a little out of breath, working your heart, working your lungs, getting stronger—but not to the point of exhaustion or pain. If it hurts, stop!"

Core exercises really are the core of pregnancy workouts

"ACOG doesn't want you exercising on your back after the first trimester because of hypertensive syndrome. They are worried that you could cut off oxygen to the baby. So many women think that means no core exercises—but it doesn't. Core exercises (like planks) are really the most important thing to do to prepare for childbirth."

Posture is key

"So much of being pregnant is about being pulled forward. As your uterus and baby start to grow, your hips are going to start to tilt forward, hip flexers are going to start to shorten. As your breasts grow, your shoulders start to come forward. Your scapula and upper back are going to get all stretched out and your pectoral chest muscles are going to start to shorten. Then it's a domino effect and the head comes forward with rounded shoulders and swayed back. To counterbalance all of that, you need to focus on back-strengthening and chest-stretching exercises. The funny thing is that post-baby, we always focus on losing the baby weight, but if you have good posture, it looks like you've already lost five pounds!"

Check out these four safe and easy workouts for pregnancy! But always make sure to speak to your OB or midwife before starting a new exercise routine.

TELL US: What's your pregnancy workout routine?

Image of pregnant woman working out courtesy of Shutterstock.