Molly stood in only her bra and knickers before the full-length mirror in the bedroom. She surveyed her reflection carefully as her teeth nibbled nervously at her lower lip.

When Sherlock came up behind her and wrapped his arms around her, she knew he'd deduced it. He gently rubbed her stomach, nestling his head in the curve of her neck, his chin coming to rest on her shoulder as he captured her gaze with his own.

"I'm sorry," she said. "I have no idea how this happened…" Tears began to well up in her eyes.

An elegant eyebrow arched in surprise. "You don't?" he asked playfully.

When she shook her head the tears rolled down her cheeks, her expression a mixture of confusion and uncertainty.

Sherlock turned his head so that his lips rested against her sensitive ear. "Would you like me to remind you?" he enquired, the timber of his voice sending shivers up and down her body.

Molly's eyes widened with surprise. "You're not upset?"

Sherlock frowned. "Why would I be upset?"

"Because we've only been in a relationship for three months," she replied.

Sherlock didn't respond with words. Instead he turned her around and picked her up and carried her over to their bed and laid her down upon it.

When they were both naked he placed the gentlest of kisses on her still flat tummy, before covering her body with his own. Taking her face in his hands he leant down and kissed her passionately on the lips as he slowly entered her.

He was determined that by the morning she would be left in no doubt of his feelings concerning the amazing changes that were about to happen in their lives.

Ever the scientist and detective, Sherlock kept detailed notes of all the changes that were happening to Molly and their baby as the pregnancy progressed.

Everything from the varying symptoms of pregnancy and how they affected Molly on an emotional, physical, sexual and psychological level, through to the development of the foetus.

Molly's mood swings, weight gain, cravings and the constant changes to her body as their baby developed within her were of constant fascination to him.

He kept detailed notes based on the ultrasounds, though they had both decided that they didn't want to know their child's gender until the birth, Sherlock was happy to make his own deductions based on the information he'd gathered.

"You can't call working out our babies gender a deduction," Molly laughed.

"Why not?"

"Because it will either be a girl or a boy. You've got a 50/50 chance of getting it right."

Sherlock pouted. "But I'm using scientific, deductive reasoning in coming to my conclusions."

"Of course," she said, kissing him gently on the lips before she headed towards their bedroom. "I'm going for a lie down. Care to join me?"

Sherlock willingly followed her.

And Molly took note of the changes in Sherlock.

She noted his curiosity, hence the need for the constant note taking regarding every aspect of the pregnancy.

His concern over whether she was eating, resting, exercising and sleeping enough. He really was turning into a mother hen. It was a side of him she'd never witnessed before. It was endearing, frustrating at times, but oh so adorable. These precious details she kept safe in her journal.

Whenever she felt annoyed or exasperated by Sherlock's constant need for data, she took a calming breath and reminded herself that he did it all out of love, for her and their unborn child.

Though she did have to stop him interrogating her doctor, who had threatened to have him banned from attending her appointments with her.

As her pregnancy progressed she watched his initial excitement at the idea of becoming a father turn to one of anxiety. She knew he fretted over whether he would make a good father. He read countless books and online articles on the subject, and whatever information he found there left him feeling inadequate to the task.

In the end she had led him to their bedroom. Standing once again in front of the full-length mirror with Sherlock standing behind her, his arms wrapped protectively around her expanding tummy, Molly met his gaze in the mirror. "You will be a wonderful father Sherlock, just you wait and see," she said.

"You really believe that?" he asked uncertainly.

Molly turned awkwardly and pulled his head down to her. "Yes, I do."

Sherlock smiled softly and leant down to place a gentle kiss upon her lips.

For all his measuring and note taking there was one calculation Sherlock got wrong.

When his baby daughter would make her arrival.

Elizabeth Margaret Holmes made her appearance at just on 37 weeks. Despite all the available information concerning the length of time from the beginning of the contractions to the actual birth, Lizzie was in such a hurry to arrive that they never made it down the stairs of Baker Street.

Sherlock and Molly lay in their bed, wrapped in each other's arms, their daughter snuggled securely between them.

After all the chaos she had caused, Lizzie now slept utterly content, lulled by the reassuring beat of her parent's hearts.

Molly and Sherlock watched her as she slept, sharing contented smiles as they pictured the wonderful adventures that lay ahead of them, now and into the future.