The 32-year-old had given birth nine years earlier to Riley Kenny, who was a healthy 10lbs.
But nothing could prepare her for Eden Rose, who at 11lbs 5oz is bigger than the average two-month-old and needs clothes for babies between the ages of three and six months.
Eden Rose, who was delivered naturally last Wednesday, was the second biggest baby the midwife at Worthing Hospital had seen in 20 years, just one ounce less than the heaviest.
Lynette, from Durrington, said: “We thought she wasn’t going to be small, but I didn’t have any growth scans after 20 weeks, so we weren’t aware how big she would be.
“They didn’t think I would have a small baby but never did they think 11lbs 5oz – no way. They were shocked. They had to get another weight conversion chart because she was off the chart.”
The birth of Eden Rose Kenny was made all the more poignant, as Lynette has polycystic ovaries and was told she might never get pregnant again.
“I was very, very shocked.
“I’m so happy. I still cannot believe it even now,” she said.
Partly because of her size, Eden Rose has been sleeping consistently since she came home from the hospital.
But a larger-than-average baby does not come without some drawbacks, as all newborn clothes needed to be traded for three and six months old clothes.
With nine years between them, Lynette had worried Riley might be unsure about having a baby sister to share things with, but she said nothing could have been further from the case.
She added: “He’s so proud of her, he’s always kissing and being kind to her.
“He’s been wonderful with her, so gentle and caring.”