After designing lingerie for five years, I’ve learned so much about pattern fitting and alterations.  I’ve seen some of the same fit issues over and over again, and while I attributed them to other things, I’ve come to realize many people need to make adjustments for pelvic tilt.  Pelvic shape and tilt, and how it affects the fit in garments, seems to be a complex subject and something I’m still wrapping my brain around.  I am going to try to make it simple here for this tutorial so I can help you get the best fit for your underwear.  At the end of the post I’ll link to where I found my information, if you want to do a more in-depth dive.

The most common fit issues I’ve seen are a result of anterior pelvic tilt, where the pelvis tilts forward.    I actually have the opposite problem; due to hypermobility and many years of dance classes, my pelvis tilts backwards if I forget my posture and lock my knees.  In the photos below I am forcing my pelvis to tilt in different directions so you can see the difference.  If you need some help figuring out your own pelvic tilt, I’ve noticed it becomes most obvious in striped underwear.  Photograph yourself from the side (I use the timer function) near a doorframe to help get a reference for true vertical.

 

The first is anterior pelvic tilt, where the pelvis tilts forward.  The side seams are very tilted, and the waistline slants down.

Second is a neutral pelvic tilt.  There is naturally some tilt (about 21 degrees) and the waistline tilts slightly forward.

Last is posterior pelvic tilt.  This is what my body wants to do when my knees lock and bend backwards a bit.  You can see my side seams are nearly vertical and the waistline is quite straight.  If I’m not careful I’m likely to topple backwards.

Now that we know the difference in types of pelvic tilt what to do about it?  Here are a few symptoms of anterior pelvic tilt and some pattern adjustments that will improve the fit.

Anterior Pelvic Tilt Symptoms:

• side seams look very angled when viewed from the side
• the front waistline dips down and the back waistline is quite high
• the gusset feels like it isn’t in the correct position, too far back in the front and too high up in the back
• the gusset might feel too wide and have wrinkles; while it’s possible it is too wide for your shape, it is also not in the correct position on the body and that should be addressed first.
• the leg line feels too low, cuts into the leg crease
• not enough bum coverage or the wedgie feeling in the back

Anterior Pelvic Tilt Solutions:

• change the gusset position to match the body shape; move it forward by shortening the front
• maintain the waist-to-waist length if the back waist position is good by adding length to the back
• adjust the waistline curve

The first step is to determine how much shorter to make the front.  You can measure how much you want the gusset to move forward so that the seam lands in the right place, or how much you want to raise the leg line.  If you aren’t sure, try 1/2″/12mm to start.  Cut across the front somewhere above the gusset seam, before the leg line starts to turn horizontal.  Overlap the pieces the desired amount and blend the edge into a new legline.

 

The gusset position is now moved forward.  If the back waistline was too high, you might not need to make any further adjustments.  If you want to keep the current back waistline you will need to add some length to the back, the same amount the front was overlapped.  Cut above the gusset seam, where the full part of the bum curve is.  We want to maintain the bum curve width.  Spread the pieces and blend the back legline.

Let’s compare the original and adjusted pieces.

At this point, you will probably want to make another fit sample to see if you need any more adjustments.  Check the gusset position and width; is it in the correct position on the body?  Is it too wide or too narrow? Is the leg line the correct height?  Do you still have a wedgie feeling in the back?

 

Further adjustments that might need to be made:

• raising the front waistline
• lowering the back waistline (opposite of raising the front waistline)
• adjusting the gusset width
• adjusting back coverage

For more information, see the following articles about pelvic shape and tilt.

Pattern School Online – Pelvic Tilt

The Sewsialists – All Butts Welcome (this is a web archive)

Lilypadesigns – Pelvic Shape and Underwear

 

I hope this tutorial has been helpful!