Shapes and fills compared

What does each comparison here rest on?

Seller pages, read and counted on a stated date, and published research. No pillow was weighed, timed or slept on for a comparison.

Two kinds of source sit under every comparison. The first is the seller's own page, read on a named date and counted: how many state a size, a fill, a weight or a washing rule. The second is published research and clinical advice, from obstetric bodies to sleep studies. Each figure links to the page it came from.

Where a column says what a shape is likely to do, it is labelled as judgement. That judgement comes from the stated sizes and fills, and from the mechanics the research describes. No maker publishes these comparisons, and none of them ranks products.

The counts are small, and they are counts of claims. Ten seller pages were read for the U-shaped comparison and five for the weighted one. A count shows what a shopper is told. It cannot show how a pillow feels, which is why the method is written out on the method page.

How much bed does each shape take?

A straight pillow takes about a third of a queen's width, a wide U takes half, and a wedge takes the least of any shape.

A queen mattress is 60 inches wide (Avocado mattress size guide). The common straight insert is 20 by 54 inches (Walmart). A wide U runs about 30 inches across (Regalo), and one Boppy C shape is listed at 26 inches wide (Lullabye Shop). One belly wedge is listed at 13 inches wide (Dillard's). The shares in the table are our arithmetic from those widths.

Width is what a partner feels. On a queen, a wide U takes exactly one sleeper's half, and the other half stays free only while both people stay put. On a full, which is 54 inches wide, a partner is left with less than a twin. A straight pillow or a C shape pushed toward the edge leaves more room.

How do the common fills compare in a long pillow?

Fiberfill is light and fixed, shredded foam and latex can be made higher or lower, and wool and feather pack down more over a year.

The fill sets the knee gap, so it shapes how well a long pillow does its main job. One fiberfill insert lists 38 ounces of polyester (Walmart). Coop says its shredded foam body pillows can be made soft and fluffy, or firm (Amazon, Coop Home Goods). A goose down and feather pillow lists a 74 ounce fill weight (Walmart, Pillowtex).

Natural fills hold your knees level in much the same way. Woolroom lists 53 ounces of washable wool balls in a 20 by 54 inch pillow (Woolroom). Savvy Rest lists about 10 pounds for its 17-inch shredded latex body pillow, and calls it its most supportive one (Savvy Rest). Weight in a listing is the plainest clue to how much material will sit between the knees.

How do a C shape and a straight pillow differ for one-side sleepers?

A C shape wraps the head, bump and knees along one side and flips to turn. A straight pillow holds the knees and arm in less room.

Both shapes do the main job, which is holding the top knee level with the hip. ACOG describes that setup as one or both knees bent, with a pillow between the knees or a full-length body pillow (ACOG). The difference is what else each one holds. A C adds a curve under the head and a section along the back or the belly.

That extra curve costs width and weight. One Boppy C shape is listed at 48 by 26 by 7.5 inches (Lullabye Shop), against 20 by 54 inches for a common straight insert (Walmart). To change sides with a C, a sleeper lifts it and turns it to face the other way. A straight pillow comes over in one movement.

For someone who mostly stays on one side, the two give similar help to the hips. A straight pillow with an ordinary pillow tucked behind the back builds most of what a C shape offers, and the pieces can be moved apart on a warm night.

How do covers and washing compare across the shapes?

Straight pillows take a standard case. Curved shapes need their own cover, and some of the larger ones will not fit a home washer.

A straight insert in the common size takes a case cut to it, and one such case closes with an inner flap instead of a zipper (DOWNSTORIA case, Amazon). That makes a spare cover easy to find. Curved pillows are sold with covers cut to their own shape, so a spare has to come from the same maker.

Washing the whole pillow gets harder as the shape grows. Boppy's page says its Total Body pillow fits in most washing machines, while its care notes say to use a commercial-size washer or dryer (Boppy). Leachco says to spot clean its Snoogle and machine wash only the cover (Leachco).

Fill changes the answer as well. Coop says both its shredded foam body pillow and its outer cover are machine washable (Coop). Glass beads in a weighted pillow get heavy when wet, so the cover is the part that goes in the machine. In every shape, a removable cover keeps the routine simple.

Does a cooling cover beat an ordinary one over a night?

At first touch, yes. Over a night, cooling fabric warms toward skin temperature, and only 2 of 9 listings read gave any cooling figure.

A review of nine studies found that cooling mattresses and toppers did not change measured sleep stages (Frontiers in Sleep). A cover is a thinner layer still. The room does more of the work, and a Cleveland Clinic sleep specialist says 60 to 67 degrees Fahrenheit is often recommended (Cleveland Clinic).

Shape changes heat as well. A U presses fabric against the front and the back at the same time, while a straight pillow leaves the back open to the air. The figures, and what a Q-max number on a cover means, are in Does a cooling body pillow keep you cool all night?

How do the shapes compare across the months of a pregnancy?

A wedge or straight pillow suits the second trimester, and a C or U earns its bed space once the belly and hips both need holding.

The shape a pregnant sleeper needs changes over the months. ACOG says side sleeping may be best in the second and third trimesters (ACOG). Early on, a wedge or a straight pillow between the knees covers most aches. Later, a curved shape holds the bump, the back and the knees at once.

No trial has compared shapes against each other, so this is judgement drawn from what each shape holds. The one trial of a pillow built to stop back sleeping found it did not cut time on the back (Wilson et al., BJOG). The back section of a U or C mainly makes side sleeping more comfortable to keep.

The stage-by-stage view, with the weeks behind it, is on Pregnancy pillows. That page also covers what a wedge holds up and where each part of a curved pillow goes.

When does the second arm of a U earn its width?

When a sleeper turns often or keeps rolling onto the back. For one-side sleepers, a straight pillow covers the knees and arm in less room.

A U puts one arm down the front and another down the back, so a sleeper rolls over and finds the other arm already there. The sleeper never has to haul a pillow across the bed. A straight pillow either turns with the sleeper or stays behind on the old side. That single difference decides most of the comparison.

On the ten seller pages read for the U guide here, stated lengths ran from 47 to 59 inches. Two of the shorter ones were narrow enough to be a gently curved long pillow rather than a U to lie inside. One wide U lists an item weight of 8.6 pounds (Queen Rose), and that weight is what you lift at every turn in your sleep and at every wash.

For pregnancy, the back arm gives something to settle against, but no trial shows it keeps a sleeper off the back (Wilson et al., BJOG). A long pillow in front with an ordinary pillow behind does much of the same work. The full comparison, with bed widths, is in How does a U-shaped body pillow differ from a long straight one?

What does weight add to a body pillow that foam does not?

Pressure to hug. Glass beads in sewn pockets press along the side, while foam fills a wider case and holds the knees apart.

The weight is the pressure you feel along your side as you fall asleep. On five seller pages read for the weighted guide here, two named glass beads as the weight, one named flaxseed, and two named no material. The full-length weighted pillows weigh between 6.5 pounds (Zonli) and 10.8 pounds (Shloof). Most are narrow tubes. The largest weighted size read was 48 by 14 inches, against 20 by 54 inches for one shredded foam pillow (Coop).

No trial has tested a weighted body pillow. The evidence sellers cite comes from blankets. In one trial, 120 patients were given an 8 kilogram or a 1.5 kilogram chain blanket for four weeks (JCSM commentary, PMC). A hugged pillow puts far less weight on a far smaller area.

Weight helps in one plain way: a heavy pillow stays where it was put. It never belongs near a sleeping baby. The beads, the sizes and the safety limits are in What is inside a weighted body pillow, and how does it differ from memory foam?

Which head-to-head questions are answered in full?

• How does a U-shaped body pillow differ from a long straight one?
• What is inside a weighted body pillow, and how does it differ from memory foam?

Common questions

Is a U-shaped pillow warmer than a straight one?
Usually. A U puts fabric against the front and the back at once, while a straight pillow leaves the back open to the air.

Can a straight pillow do what a C shape does?
Much of it. A straight pillow holds the knees and the arm. Adding an ordinary pillow behind the back gives the wall that a C shape builds in.

Is a weighted body pillow safe near a baby?
No. Pediatric guidance says to keep weighted products and soft items away from an infant's sleep space.

Which fill keeps the same height longest?
Of the common fills, shredded latex springs back most after each turn. Fiberfill and wool pack down more, which an adjustable zipper can offset by adding fill back.

Sources

Gathered here, the outside pages this body pillow guide quotes, each beside the part of the guide that needed it.

1. Avocado mattress size guide (help.avocadogreenmattress.com), needed in “How much bed does each shape take?”.
2. Walmart (walmart.com), needed in “How much bed does each shape take?”; “How do the common fills compare in a long pillow?”; “How do a C shape and a straight pillow differ for one-side sleepers?”.
3. Regalo (regalo-baby.com), needed in “How much bed does each shape take?”.
4. Lullabye Shop (lullabyeshop.com), needed in “How much bed does each shape take?”; “How do a C shape and a straight pillow differ for one-side sleepers?”.
5. Dillard's (dillards.com), needed in “How much bed does each shape take?”.
6. Amazon, Coop Home Goods (amazon.com), needed in “How do the common fills compare in a long pillow?”.
7. Walmart, Pillowtex (walmart.com), needed in “How do the common fills compare in a long pillow?”.
8. Woolroom (thewoolroom.com), needed in “How do the common fills compare in a long pillow?”.
9. Savvy Rest (savvyrest.com), needed in “How do the common fills compare in a long pillow?”.
10. ACOG (acog.org), needed in “How do a C shape and a straight pillow differ for one-side sleepers?”.
11. DOWNSTORIA case, Amazon (amazon.com), needed in “How do covers and washing compare across the shapes?”.
12. Boppy (boppy.com), needed in “How do covers and washing compare across the shapes?”.
13. Leachco (leachco.com), needed in “How do covers and washing compare across the shapes?”.
14. Coop (coopsleepgoods.com), needed in “How do covers and washing compare across the shapes?”; “What does weight add to a body pillow that foam does not?”.
15. Frontiers in Sleep (frontiersin.org), needed in “Does a cooling cover beat an ordinary one over a night?”.
16. Cleveland Clinic (newsroom.clevelandclinic.org), needed in “Does a cooling cover beat an ordinary one over a night?”.
17. ACOG (acog.org), needed in “How do the shapes compare across the months of a pregnancy?”.
18. Wilson et al., BJOG (pmc.ncbi.nlm.nih.gov), needed in “How do the shapes compare across the months of a pregnancy?”; “When does the second arm of a U earn its width?”.
19. Queen Rose (queenrose.com), needed in “When does the second arm of a U earn its width?”.
20. Zonli (zonlihome.com), needed in “What does weight add to a body pillow that foam does not?”.
21. Shloof (shloofpillow.com), needed in “What does weight add to a body pillow that foam does not?”.
22. JCSM commentary, PMC (pmc.ncbi.nlm.nih.gov), needed in “What does weight add to a body pillow that foam does not?”.