So I have a sizing question that you may be able to answer... What is the minimum neck opening circumfrence that a child needs to get a garment on over their head? I've always thought that it was 18". Is this correct???Babies are very interesting. Most babies have the head circumference that they will have as adults. There is some growth that occurs between newborns and older babies as the bones in the skull begin to fuse and the head takes shape. Other factors that contribute to head size are genetics and weight. A newborn baby's head circumference may start as small as 14 inches but grow to about 20 inches by age 2. Proportionally, babies appear top heavy because the head looks too big in comparison to the rest of the body.
When designing clothing and patterns for babies, there are some other considerations. Babies do not dress themselves. This means someone else must be able to reach into a shirt, for example, and comfortably pull it over the head. With a dress, you have to reach down through the neck and pull a dress over the hips and ultimately over the shoulders. Some degree of space must be included to allow for ease in dressing (as quickly as possibly too!).
The recommended head opening for children's clothes is 20 inches for all infants and 21-22 inches for toddlers and up. This is a minimum measurement. Additional ease may be required depending on the fabric and/or style. This recommendation comes from my experience working with big box retailers - and they all seem to agree on this point. Over the years, I have seen that this is the measurement that is actually needed. BTW, this measurement refers to the extended neck measurement (see pictures below). There is no US government regulation that I know of - this is an industry standard. You can measure lots of product yourself to see most things follow this guideline.
Incorporating 20 inches into a neck circumference can be very difficult. The assumption is made that the neck circumference of the pattern must meet 20 inches. A neck circumference on a baby is 12-14 inches (measurement taken at the base of the neck). If your pattern has a neck circumference of 20", then your garment will probably fall off. The extra girth needed to meet the extended neck circumference can be added by the addition of a front or back placket, zipper, button placket, lapped shoulders, elastic, or stretchy neck ribbing. In other words, make the neck of the pattern where it should be and add extra length/girth somewhere else.
Here are few pictures of me measuring the extended neck circumference of a few different styles. Please note, I used a tape measure because it shows up better in the pictures. You should probably use a flat ruler instead. Plus, DH was taking the pictures off to the side, so it appears that I am not lining things up right, but I am. To measure the extended neck circumference, place one finger in the center front neck and another in the center back and stretch. Double the measurment from the ruler and you will have the extended neck circumference. If drafting a pattern, you can measure the pattern neck circumference plus any additional opening. It is best to double check a measurement after a garment is sewn up because things change.
This shirt has an elastic neck. Stretch the elastic as far as it will go without damaging it. You can see this neck measures about 22" extended.
This infant polo shirt has a front button placket. You can see this shirt stretches to 20".
This infant t-shirt only stretches to about 18". It is a bit tight IMO. Part of the problem is the stretch of the ribbing and also how it is stitched to the neckline. The topstitching prevents stretching beyond this point and could actually break if I take it any further.
To measure the neck opening of a dress, measure from the center front neck to the bottom of the skirt placket opening. The extended neck measurement needs to be larger because the waistline needs to either slip over the head or the hips easily. This measures about 26 inches.