FORT WORTH, Texas -- Mackenzie McCollum was about four months pregnant as she darted around the volleyball court, angling to get under the ball in her team's first game of the district playoffs.
Although her team lost that Nov. 3 contest, simply getting to play was a victory for the 17-year-old senior, who battled several obstacles to get back on the team at Arlington Heights High School in Fort Worth, Texas. Among the many issues raised was concern about whether being that active was good for her and her baby.
"I've had times where I've been short of breath on the court after a long play, but that's [it]. I've had that even when I wasn't pregnant," Mackenzie said. "But I've never actually felt sick while playing."
Although Mackenzie's case is unique because of her young age, her desire to stay active as a pregnant athlete is shared by women among all athletic ranks, from amateurs to collegiate competitors to Olympic and professional players, such as Olympic beach volleyball gold medalist Kerri Walsh and WNBA star Candace Parker, who both had babies in May.
LPGA player Catriona Matthew was five months pregnant in January when she won the Brazil Cup. Then, 10 weeks after giving birth, she won the Women's British Open.
Despite the successes of some sporting moms-to-be, controversy and uncertainty remain as to whether pregnant athletes should keep playing and training or should consider pregnancy as nine months on the disabled list.
"I strongly believe pregnancy should not be a state of confinement," said Dr. Raul Artal, chairman of obstetrics, gynecology and women's health at Saint Louis University in St. Louis. "If there are no complications, and a woman is willing to continue to train, she can."
For more than 30 years, Artal has researched the impact of exercise on pregnancy and has written several books on the topic for amateur and professional athletes. He's worked with several well-known athletes as they've kept up their sport while waiting to deliver, including a runner who trained for the Olympic trials while pregnant.
It's a bit ironic, then, that Artal is the reason so many other obstetricians impose physical limits on pregnant athletes that make it almost impossible for them to do much more than a casual jog.
In 1985, Artal said, he and other doctors suggested guidelines to the American College of Obstetricians and Gynecologists to have pregnant women keep their heart rate below 140 beats per minute during exercise. The concern, Artal said, was that the fetus would be deprived of oxygen if a woman's heart rate went any higher.
When Parker was pregnant, it was easy for the 23-year-old pro basketball forward to sometimes creep up to 170 beats per minute on the elliptical machine. She said she could hit 140 beats per minute just walking, which wouldn't give her, or most other pregnant athletes, much of a workout at all.
Artal said that, in 1985, he and another doctor used intuition and calculation to determine the 140 beats rule. Six months later, when actual testing of women in a lab proved them wrong, Artal said he asked for the 140 beats notation to be stricken from the guidelines.
"For some reason, people caught onto that and they never let go," he said. "Each time I get asked about it, I said forget about it. I think it should be ignored."
Ideally, pregnant women should keep their internal core temperature below 103 degrees Fahrenheit, but Artal acknowledges that is almost impossible for an average person to measure. Instead, they should just stay hydrated, be aware of the change to their center of gravity and maintain a workout pace that allows them to breathe easily. To this day, he said, there is no standard limit to how high a woman's heart rate should be in pregnancy.
Yet decades later, the 1985 guideline keeps getting picked up. It filtered its way into medical textbooks and has become the uncorrected lexicon of legions of obstetricians. In fact, a Google search on the topic of pregnant athletes and exercise brings up a pregnancy Web site where Artal's more current advice is countered by another obstetrician recommending the 140 beats rule.
And it was the initial advice that Dr. Jay Herd, a Fort Worth ob-gyn, gave to Mackenzie, the high school volleyball player, when she came into his office on Oct. 16 to get a medical clearance to play volleyball. He acknowledges it was more out of habit than anything else, and he equated it to the old adage of drinking eight glasses of water per day.
"That wasn't really evidence-based recommendations. It's just been passed down," he said. "Now we just tell them to be reasonable with their heart rate. If they're used to a heart rate of 145 when they're working out, and they can do that without getting overheated, or dehydrated, then that seems to be safe."
His initial note also said Mackenzie was to have "no contact," which he didn't think was a problem because he didn't consider volleyball a contact sport. Also, Mackenzie said she had adjusted her playing style to make sure she didn't have to dive for the ball and risk hitting her stomach on the floor.
When Fort Worth school district officials got the note, they wrote a letter to Mackenzie's mother saying the girl still couldn't play because they deemed volleyball a contact sport and said they had no way of monitoring her heart rate. A few parents also complained, saying they didn't think it was safe for her to be on the court. Herd, who said he was surprised at the school's reaction, wrote a second note clearing Mackenzie to play with no restrictions. She was back on the court the next day.
Fort Worth school district officials declined to talk about Mackenzie's case, citing a district rule that prevents them from publicly discussing a specific student's medical condition. But a spokesperson said this was the first time they had to deal with this issue in terms of a pregnant athlete wanting to continue playing sports. Although there are no statistics on pregnant student-athletes, the number of births to teenagers ages 15 to 19 went up between 2005 and 2006 after having steadily declined for 15 years. In 2006, about 4 percent of teens -- or one in every 25 -- gave birth, according to federal statistics.
Although Mackenzie's age puts her at a higher risk for complications and premature labor, Artal said he would simply tell her to keep doing what she's doing as long as she's under close medical supervision, which is basically what Mackenzie, her mother and Herd eventually agreed to, as well.
Artal said his best advice for pregnant athletes is to use common sense.
"It's strictly a matter of judgment and how much an individual wants to take risk," he said. "There is no evidence that physical activity is bad for the fetus." Advancements in fetal monitoring can help a doctor determine whether an athlete -- or any woman -- needs to slow down, he said.
When Parker found out she was eight weeks pregnant in October 2008, her season with the L.A. Sparks was over, but she was scheduled to play overseas for a Russian club in her offseason. She canceled those plans, but immediately set an ambitious goal to rejoin her WNBA team in June.
Working with her doctors, she developed a training routine that consisted of shooting at least 300 times every day and spending 30 minutes on the elliptical machine three times a week, keeping her heart rate in the range of 160 to 165 beats per minute.
"I'm not going to lie. It was tough to not overexert myself," she said. Sometimes her husband, Boston Celtics forward Shelden Williams, would eye his wife's heart rate monitor. "It was 175 or something, and he's saying, 'Babe, you need to slow down.'"
Her pregnancy workout was about 60 percent of her regular workout, she said, adding that she kept up her shooting and cardio routine until just three days before giving birth. She had been lifting with 10- to 15-lb dumbbells until the final three months of her pregnancy, as well. She did not, however, play a single game.
"I didn't want to get knocked down," she said. "You see women fall all the time. If something would happen, I would never forgive myself."
She gave birth on May 13 to Lailaa Nicole Williams, and just weeks later met her goal of returning to the team. She made her post-pregnancy debut on the court in a July 5 game against Phoenix during which she played about 20 minutes. She said she didn't feel 100 percent, though, until a game against Sacramento in early August.
"Before, I was making moves and they were staying right with me," she said of her opponents. "I made a move in this game, and I was actually losing people. I was excited I was getting my timing and my quickness back."
Recovery took longer for professional soccer player and two-time Olympic gold medalist Kristine Lilly, who had a cesarean section to deliver her daughter, Sidney Marie Heavey, on July 22, 2008. Lilly now plays for the Boston Breakers professional soccer team.
When she first found out she was pregnant, the now 38-year-old athlete flirted with the idea of retiring, but decided that she needed more of a goal than teaching kids and holding clinics. She wanted to be a part of the Women's Professional Soccer league when it launched in spring 2009, and she planned to try to get back on the U.S. national team.
To stay in shape, Lilly said she just took her current workout down a notch. She heard about the 140 beats per minute rule from some friends, but her doctor never mentioned it.
"He just told me, 'Don't overexert yourself. Don't work out like you're training for something,'" she said. "He said, 'You're in great shape. Just make sure you eat well, drink water and live the way you've been living.'"
It was hard for her to dial down her workout in the beginning, especially on the treadmill, she said, and it was quite an adjustment to see that she was gaining weight at the gym.
"I had to remember that that was OK. That it's OK I was doing it at 9 speed instead of 10 speed," she said. "It kicked in that I was having a baby, and the baby's health was more important."
At 12 weeks, Lilly did play in a fundraising game in Los Angeles for her friend and former teammate Mia Hamm, who was raising money for her own charitable organization. But Lilly took precautions.
"I played very little," Lilly said. "There was one time someone was about to take a shot and I turned my whole body backward. 'Don't hit my belly.'"
Paula Lavigne is a reporter in ESPN's Enterprise Unit. Her work appears on "Outside the Lines." She can be reached at email@example.com.