Doctors, nurses, researchers and state lawmakers are investigating a mystery -- why Texas women die after giving birth at a higher rate than anywhere else in the country.

"It's hard to remember details because I was pretty upset," said Chris Zavala, 39, when recounting what happened to his wife Michelle last month.

She was 35, active and adventurous.

"You always hear about love at first sight, and it sounds corny, but the first time I saw her, I was done for,” he admitted.

Their first child, Clara, was born mid-July. She was healthy, six pounds and four ounces.

At 7 days old, they took her to pose for newborn pictures, never imagining their first family portraits would also be their last.

"She actually looked on her phone the symptoms of a heart attack and she knew she had all those symptoms. The tightening of the chest and she felt nauseous,” said Marsha Hodnett, Michelle’s mother.

"They said she had a pulmonary embolism. I wasn't sure exactly what that meant,” added Paul Hodnett, Michelle’s father.

A pulmonary embolism is a blood clot. Michelle had one that moved from her leg to her lung.

Looking back, Chris said, the only indication Michelle might have had was a swollen leg a couple days after giving birth to Clara.

She went to the emergency room, but doctors couldn't save her.

"I just remember crying, watching them perform CPR on her,” continued Chris.

Michelle is from Pflugerville but grew up in Hudson Oaks, outside Weatherford, where her parents still live.

"I said ‘I need to go mow my yard.’ Everybody said, 'No don't go mow your yard.' 'I've got to mow the yard. I just need to mow the yard. I had to cry mowing the yard. I talked to God mowing the yard,’” said Paul Hodnett, fighting back tears.

New mothers die in Texas at a higher rate than anywhere else in the country. Most from heart-related problems like what happened to Michelle.

But why is it happening? Could it be that there are fewer health clinics for women in this state? No one yet understands the trend.

"I don't think there's anything you can do to ensure that you're not going to encounter those problems. Pregnancy in and of itself is a risky thing. Even though we think of it as the best time in our life, it's also one of the riskiest times in our life as far as our health is concerned,” said Dr. Theresa Patton, a OB-GYN at Methodist Dallas.

That's what's scary. Pregnancy can mask symptoms of heart disease.

"It's really hard to discern heart disease in pregnancy from typical pregnancy symptoms. So, all the things we would tell the general population -- fatigue, shortness of breath, swelling of the legs, all of those things happen in pregnancy anyways. What I worry about is if it's persistent and severe,” added Patton.

"If we are truly standing out in notable fashion from other states, then we're missing something. So let's figure out what that is and correct it,” said State Rep. Cindy Burkett, R-Sunnyvale.

The state started studying the problem several years ago and discovered heart failure is the leading cause of death among new mothers in the year after child birth. Black women bear the greatest risk.

Experts suggest prenatal care and warned women not to skip follow-up appointments after giving birth.

Last week, the Texas House voted to keep that study going until 2023.

"I think the most exciting part about it is with all the things we've looked at over the last few months, this is a bi-partisan issue that everybody is interested in finding solutions for,” said Rep. Burkett.

Chris Zavala is raising a daughter without a wife. He’s still uncertain what he'll tell Clara about the mother she never knew.

“I will probably tell her that her mother loved her very much and even for just those eight days she had her, she loved her a lifetime,” he said.