In fact, academics from Newcastle and Bristol universities found that attendance improved after pregnancy among more than half of school-aged mothers.
Major factors in the turnaround were the specialist units and out-of-school provision which more than half the girls interviewed had used.
Smaller classes, more flexible and often shorter timetables, greater choice over what subjects they studied, and being treated like adults were all cited favourably by those surveyed.
The report quoted Abigail, 16, saying: "It's OK here, different like, you know, no uniforms and none of them stupid rules. If they tell you something here, there's like a good reason and that, it's more relaxed and more grown-up, they speak to you like grown-ups."
Of the 93 girls interviewed, all pregnant before they were 16, only 38 said they attended school regularly around the time of conception.
But after their babies were born, attendance improved for 52, according to the study commissioned by the Department for Education and Skills. Fifty girls said education was more important to them and a further six said they liked it more than previously.
Pregnancy was viewed as a generally positive experience by 58 pupils. Most mainstream schools the researchers spoke to said they saw young mothers staying on as illustrating their caring nature.
But half of the pupils reported negative attitudes from schools. Of 80 answering the question, 42 said they were offered no help to stay on, with many believing they were being deliberately forced out.
"I got the feeling pregnancy was infectious," said 16-year-old Sarah. "They did nothing to help."
Schools had told 19 of the interviewees to leave, with health and safety and the school's reputation being common justifications.
The report commended the work of reintegration officers, used in areas with high teenage pregnancy rates to support young mothers in education, and called for enough funding for them to be introduced in all local authorities. A DfES spokesman said the vulnerable children grant, currently funding such measures, was being replaced, but the support would continue.
The education of pregnant young women and young mothers in England, N. Dawson and A. Hosie, Bristol university leader 22
WHAT KATIE DID NEXT
Pregnancy at 13 transformed Katie's educational prospects - for the better.
The Bolton teenager had been enrolled at three secondaries by the time she reached Year 9 and did not enjoy any of them.
After a year's continuous absence in Year 9, Katie, pictured left, was told she would not be able to take her GCSEs because she had missed so much.
Then she became pregnant and was placed in the Young Mums Unit run by Bolton council.
She said: "I want to get up in the morning and come here because it is smaller. I get better teaching and I can get on with my work."
Today Katie, now 15, is studying for five GCSEs alongside vocational courses in computing, child development and cookery, while her baby is looked after in the creche next door. Her daughter, who is one next month, is the other factor in her mother's new enthusiasm for lessons. "I value education more having had her," said Katie."I want to go to college next year so that I can become a hairdresser."