Lisa McKay had expected morning sickness, weight gain and strange food cravings when she found out she was pregnant with her first child in 2011. But she didn't expect a nagging ambivalence over being pregnant to persist into her third trimester.

She had trouble shaking the feeling that her horizon was narrowing, that what she stood to lose was more tangible than the joys coming her way, she wrote in a blog post at seven months pregnant.

Pregnancy had already taken its toll as sleep deprivation, morning sickness and fatigue sapped her energy and ability to concentrate. She mourned the impending loss of "long, lazy dinner conversations" with her husband and the luxury of spending time as she pleased to write or pursue consulting projects as a psychologist in Laos, where she and her husband live.

In addition to concerns about labor and delivery, she was worried about juggling identities she had spent her adult life forming -- writer, psychologist, wife, friend -- to include mother, sure to be the largest role.

"I knew I wanted a family, but I was also wary of the huge change (and, frankly, the sacrifices of time and energy) that I knew a baby would bring," McKay said in a CNN iReport.

"Dominic's very existence completely reordered my priorities. I had changed significantly, and not all of those changes felt fun. They felt miraculous, and I wouldn't undo my decision to become a mother if given the choice, but they didn't all feel fun."

McKay and other CNN iReporters shared stories of lessons learned from pregnancy in the wake of some recent high-profile baby announcements. Among the thicket of blessings, nightmares and unforeseen medical complications, a few common themes emerged, chief among them that pregnancy rarely goes as planned.

Throw out the playbook

"Have an open mind, and expect the unexpected," said Renee Governale, a 47-year-old executive assistant from Charlotte, North Carolina. "I went into it thinking I was going to have a perfect birth with lots of support, music playing, and holding my baby right after he was born. It didn't go that way for me. Nothing I planned went the way I wanted it to, but my son was born healthy and I survived, and that is all that really matters."

For instance, Governale did not anticipate losing weight while she was pregnant. But after developing gestational diabetes, she started exercising one hour a day and changing her eating habits so she could avoid taking insulin shots.

"I would do 20 minutes on the treadmill in the morning, 20 minutes of walking in the city of Charlotte during my lunch hour, and then 20 minutes on the stationary bike after dinner," she said. "It was the only way to control my blood sugars after eating, without having to go on medicine."

Otherwise, yes, her ankles swelled, and her sense of smell magnified. Body odor or too much perfume could send her into an hour of nausea, she said.

"I was lucky. I never actually got sick, but was nauseous for three months straight," said Governale, who was 38 when she gave birth.

"Everything changed," as they saying goes, but it was all worth to bring Michael into the world, especially after five years of trying to become pregnant, she said. Besides the physical changes, she thinks twice before cutting off a car, speeding or making any risky moves. She's responsible for another life now.

"I remember my mom telling me when I was pregnant to enjoy my quiet time now, because my life would never be the same again. She would tell me this when I would tell her how I couldn't wait to see him, hold him, love him," Governale said.

"She was right. It does change. Some things are very difficult, but the joys outweigh any difficult times," she said. "As a parent, I feel more joy sharing his life with him that I could have ever imagined."

If she could give couples one piece of advice, it would be to not wait to conceive.

"Time is precious. Being an older parent is not so easy. Now that I have my child, I wish I had him 20 years ago sometimes, just so I had more energy," she said. 'There is never a 'right' time to become pregnant. Children bring love and joy into your home, but they are a lot of work, and require lots of energy. Don't be scared, it will all work out in the end."

Experience versus youth

McKay agreed that some youthful energy would come in handy. Pregnant at 37 with her second child, she has no regrets about delaying her first pregnancy until she was 35. The experiences she gained in her 20s and early 30s are precious to her. She lived in Croatia, earned two master's degrees, traveled throughout Africa for work and built a successful career. Plus, she didn't meet her husband, the love of her life, until she was 32.

"I do wish there were a way to have those sorts of experiences and still have children when you have all the energy and stamina and health of your early 20s, but for me, that wasn't an option," she said. "I think you just need to play the cards you're given in life and keep looking forward with minimal regrets."

However, she had to think long and hard when a 25-year-old friend recently asked whether she should have children now, before pursuing her dream of going to midwifery school, or go to school and delay having kids.

"After a great deal of thought, I advised her to have children now and delay going to school and working for a couple of years," she said in an email from Laos, where she and her 2-year-old son and husband, who works for a humanitarian development organization. "So, I guess that suggests that if it's a viable option to have children younger and then pursue some of your academic and career dreams, I do think that can be preferable to waiting until much later to have children."

Heated discussion on whether to delay

The implications of having children later in life became a heated topic recently after an article in The New Republic reported about potential negative medical consequences of delayed child-bearing.