Disclaimer: All JKR's except for my OC.
On a bright spring day, having the afternoon off, Professor Severus Snape walked toward the dungeon to see if his wife wanted to take a walk on the grounds. As he got to the last hallway, he heard a loud bang, his wife squeak, and then a thump. He ran the rest of the way to discover a dismayed Luna Lovegood, a smoldering cauldron, and his wife in a heap on the floor.
"What happened? Was anyone else in here?" His eyes were blazing.
"I don't know. I was helping to make the test potion for the OWLs this week and all of a sudden it exploded and she fainted. No one else was here."
"Did she get any on her?" He was kneeling beside her, looking for injuries.
"I don't think so."
He looked in the cauldron and saw that it was inert.
"Do you think you can clear this up?"
"Yes sir."
He scooped his wife up and carried her to the hospital wing.
"Severus..."
"I'm here, Love. We're on our way to see Poppy. Are you hurt?"
She shook her head. "So dizzy."
"Almost there. POPPY!" He yelled for Madame Pomfrey.
"What's happened, Severus?"
"She's fainted, a potion went bad on her..."
Poppy Pomfrey snorted. "Classic. Here, set her down on this bed. Are you awake, Barbara? Good. Okay, Severus, I'm going to examine her while you wait out there." Before he knew it, he was on the other side of a shut door.
A few minutes later, Madame Pomfrey came out of the room, smiling enigmatically.
"Is she okay, can I see her? What's happened to her?"
"She's fine, Severus... What were your plans for starting a family?"
"We wanted to welcome life into our lives whenever it comes, now that--" It suddenly occurred to him. "You mean?"
"You have been married almost a month and a half, now."
"We're-- She's-- a baby?"
"Congratulations, Severus, you and your wife are going to be parents."
"Poppy! That's wonderful news!" And he picked her up and kissed both her cheeks.
"Severus! What happened? Some students told me--"
"Congratulate us, Minerva, dear girl! We're going to have a baby!" He embraced her, too.
The two ladies ran into the room to see Barbara. She accepted their congratulations with a smile, but her eyes searched those of her husband, who stood by the door, a look of great contentment on his face.
Professor McGonagall finally left and Madame Pomfrey fussed around Barbara for several more minutes. "I think she's well enough to return to her own room for a good night's sleep. The potion going bad is something some witches struggle with. Sometimes it resolves itself after a few months, sometimes it takes the entire pregnancy. You may want to find other ways to prepare your classes."
"We'll work it out. The term is almost over."
They were finally alone.
Severus sat on the side of her bed and kissed her thoroughly. "Severus, are you pleased?"
"Nothing could give me greater delight," he said, drinking in the sight of her.
"I'm so glad. Poppy was asking questions and then I realized..." A thought came to her. "It's not the best time."
"With Death Eaters chasing us? I cannot think of a better time to share so fully in life."
"Such optimism! I love you."
"And I, you."
Had the recently graduated Gryffindors been in the hospital wing right then, they would have seen the Snapes snogging in earnest.
A/N: Long ago, a coworker told me a story about how her family had come to Thanksgiving dinner expecting her trademark apple pie and after having one bite, which was not good, the co-worker's mother looked at her and said, "You're pregnant." Apparently in their family there was a tradition or old wives tale that a pregnant woman can't bake very well. I've never heard that one elsewhere, and it's not my own experience, but it seemed like a fun sort of "symptom" to give poor Barbara.