When Liz Clusiau weighed herself at 38 weeks pregnant and saw the number above the needle, she stopped stepping on the scale. “I started to freak out toward the end of my pregnancy because I couldn’t believe how much I’d gained,” says the Toronto mom.

Many women worry about the extra pounds they put on during pregnancy, says Dr. Paul Martyn, a specialist obstetrician at the Foothills Medical Centre in Calgary. “It’s very common for women to exceed weight-gain recommendations, but the problem is that a lot of women get too focused on it and it becomes a real issue for them.”

Dr. Martyn says the main concern is if you’re over- or underweight before getting pregnant in the first place. “It’s more important for women to get to their ideal body weight prior to pregnancy,” he says. Although, he adds, how much you gain—whether too much or too little—as well as how quickly you gain it, can affect your health. Here are some guidelines to follow to help keep your weight within a healthy range.

how much?

By the time she stopped weighing in, Clusiau had gained 51 pounds, more than 20 pounds over the average weight gain recommended by Health Canada (25 to 35 pounds if you were at your ideal weight before pregnancy, 15 to 25 pounds if you were overweight and 28 to 40 pounds if you were underweight). Most women fall into the “average” category of 25 to 35 pounds, although many find they pass the upper mark with several weeks left to go. “The most common misconception women have is that they need to gain weight right away,” says Daina Kalnins, a registered dietitian at the Hospital for Sick Children in Toronto and co-author of Better Food for Pregnancy (Robert Rose). “But you generally don’t have to gain much at all in the first three months.”

Most women should gain two to eight pounds in their first trimester and about one pound a week in their second and third trimesters. And yes, the weight-gain limits hold true for second pregnancies. For example, if you didn’t lose all the weight from your first one, you might be in a different body mass index group going into your second and therefore need to gain less weight than you did the first time around.

gaining too much or too little

“Most of my weight gain occurred in the last trimester,” says Clusiau. “It was at that point that I stopped walking as much and really succumbed to sugar cravings. But my midwife was non-judgmental — her response was that if I was eating healthy overall and feeling well, that was what mattered.”

Dr. Martyn says if a mom-to-be finds she is gaining quickly, he’ll review her diet and encourage healthy eating. “The one thing to watch out for is rapid weight gain, which is often associated with high blood pressure or gestational diabetes,” he says. And, if you’re gaining too little, you risk having a low birth weight baby or premature delivery. The goal is slow, steady weight gain to ensure your baby has enough nutrients while also reducing your risk of varicose veins, backache, fatigue and indigestion.

just enough

To maintain a healthy weight, Kalnins recommends establishing good eating habits, such as cooking for yourself and stocking up on healthy snacks for when those cravings hit. Good choices include veggies, fruit and low-fat yogurt. Moderate exercise helps too. “Even if you didn’t exercise before, there are ways to introduce it slowly, such as walking a few times a week and building on that with guidance from a physician,” she says.

And, as far as “eating for two” goes, during the first 10 to 12 weeks of your pregnancy you only need an extra 100 calories a day (a banana or half a cup of yogurt). In your second and third trimesters, your energy needs increase to an additional 300 calories a day (a whole-grain English muffin with peanut butter).

bye-bye baby weight

One disadvantage of gaining more weight than recommended is that it’s tougher to shed. “Losing it has been hard,” admits Clusiau, whose son Oliver is now six months old. But after “cutting out sweets and weight-training like a madwoman,” she’s back to her pre-baby weight.

Sydney Loney is a Toronto-based writer and co-founder of justthefactsbaby.com, a website for pregnant women and new moms. She lost her last few pregnancy pounds chasing her toddler, Charlie.