One successful pregnancy doesn’t guarantee another one. No matter how effortlessly you got pregnant the first time, things can change. It’s called secondary infertility.

1. You’re not the only one. It’s not uncommon for couples to go from fertile to not-so-fertile over the course of a few years, says Dr. Mark Perloe, medical director of Georgia Reproductive Specialists in Atlanta. In fact, 12 percent of U.S. women are experiencing secondary infertility, which is about the same rate of women facing primary infertility, according to the most recent National Survey of Family Growth by the Centers for Disease Control and Prevention.

2. There’s no one cause or treatment. “Almost every one of the things that could cause difficulties the first time can cause secondary infertility,” says Dr. Perloe. A number of things could have changed since your last pregnancy, too. For instance, genetic conditions can set in; the fallopian tubes or sperm passageways could be damaged from infection; or the ovaries may have become polycystic, which means little cysts invade the ovaries making periods irregular and could interfere with your ability to conceive.

Much like primary infertility, there isn’t a cure-all for every woman facing secondary infertility. “Treatment is diagnosis-specific,” says Dr. Perloe. For instance, if the problem is damaged fallopian tubes or abnormal sperm, your doctor will probably treat those issues first. If the issue is age, your doctor may take steps like combining ovulation induction with insemination. In some cases, there may not be a treatment.

3. There really is a biological clock. Age is a key factor when it comes to fertility. You’re older now than the first time around. “It depends on how secondary the secondary [pregnancy] is,” says Dr. Perloe. As you age, your reserve of healthy eggs is reduced. By age 40, 95 percent of the eggs you release are abnormal. “So until you get the right one, it’s going to take awhile.” On average, it will take 8 to 10 months for half of healthy 40-year-old women to get pregnant.

4. Waiting can be a mistake. Even if you didn’t experience problems before, Dr. Perloe advises getting evaluated by a reproductive endocrinologist after a year of trying, or six months if you’re over 35. If you or your partner experienced obvious physical changes since your last pregnancy, like irregular periods or testicular trauma, call your doctor for an evaluation now.

5. Get support—even if your friends aren’t sympathetic. The difference between primary and secondary infertility, says Dr. Perloe, is you may not find as much empathy and emotional support as women who have yet to successfully conceive at all. Julia Indichova, author of Inconceivable and The Fertile Female, can identify. She got pregnant at 40 on her first try. “I thought, ‘Oh, I can do this again.’” But by 42, she was dealing with secondary infertility.

“I have a vivid memory of sitting in the office of this reproductive endocrinologist and she was looking at my records saying, ‘We’ve never had a case of anyone with your test results get pregnant. You know you are really lucky. You should be grateful for what you have,’" Julia recalls. "I said, ‘I am; I’m really grateful.’ I felt like I was not understood or almost chastised for not being grateful enough for my child.” She even had a dream that she had a cancerous tumor in her uterus and that it was her punishment for wanting a second child.

Julia now runs The Fertile Heart, an ovum-mind-body program in Woodstock, NY. At 44, she naturally became pregnant and gave birth, but Julia wants to remind women there are other ways to get satisfaction out of a struggle with secondary infertility. “Whether you birth a baby or a healthier relationship with yourself; a family through adoption or becoming foster parents, you are fertile," she says. "You are turning it into an opportunity instead of something that will ruin your life.”

More about secondary infertility:

• Get support and advice from iVillagers dealing with secondary infertility
• These celebs chose surrogacy
• Get more information at the iVillage fertility center