Depression and stress. According to the National Institute of Mental Health, the median age of onset of depression is 32. The pressure-cooker lifestyle of this time is a major contributor, says Dr. Manson. Marriage, a kid or two, and a career that's in full swing add up to lots of obligations and through-the-roof stress.
Premenstrual syndrome. "This is a peak time for PMS," says Christiane Northrup, MD, an ob-gyn and author of Mother-Daughter Wisdom (Bantam). "In your 20s, your body is more resilient, so you have an easier time clearing excess alcohol and caffeine from your system and getting by on too little sleep -- all things that are known to exacerbate PMS. But that changes in your 30s, and your body starts to say, 'Hey, keep it up and you're going to hear from me!'"
Overweight and obesity. Maintaining a healthy weight is crucial at any age, but now is the time when, experts say, the scale needle really starts to climb (33 percent of women in their 30s are overweight, versus 23 percent of those in their 20s). Why? Research shows that most women never lose all of the baby weight they gained -- keeping on up to 8 pounds, on average, two-and-a-half years after delivery. Plus, in your early 30s your metabolism (the rate at which your body burns calories) begins to slow. Lack of shut-eye (due to those 1,001 daily to-dos) can also cause you to gain weight. A University of Chicago study found that sleep deprivation alters levels of the hormones in the body that regulate hunger, causing an increase in appetite.
Your Stay-Healthy Checklist
Get plenty of sleep. Most of us clock a mere 6.8 hours a night on weekdays. The hard truth is that we need more. "Sleep is crucial for women in their 30s," says Dr. Northrup. "It will do more for your mental health and body weight than almost anything else."
Relax! You can reduce anxiety simply by breathing properly, says Dr. Northrup. That means inhaling and exhaling deeply through your nose.
Strength train. In your 30s, your body begins to lose muscle and replace it with fat. Start lifting weights to reverse the process, and you'll get a big metabolic boost. That's because muscle burns four times as many calories as fat does. Twenty minutes of strength training, two or three times a week, is what most experts recommend.
Tests to Have Administered
A yearly physical, including a blood pressure check and cholesterol screening. Also, talk to your doctor about your stress levels or any feelings of depression you may have. (In this case, don't wait for your annual checkup to roll around.)
An annual Pap smear and clinical breast exam. You should give yourself monthly breast self-exams (BSEs) as well. For a how-to, log on to komen.org/bse. "Breast cancer isn't a major concern in your 30s, but you do want to become increasingly vigilant," says Dr. Manson.